Home nanotechnology. "Nanotechnology in the Modern World". How atoms rub against each other

Nanotechnology is a field of fundamental and applied science and technology that deals with a set of theoretical substantiation, practical methods research, analysis and synthesis, as well as methods for the production and application of products with a given atomic structure through the controlled manipulation of individual atoms and molecules.

Story

Many sources, primarily in English, associate the first mention of methods that would later be called nanotechnology with Richard Feynman's famous speech “There's Plenty of Room at the Bottom”, made by him in 1959 at the California Institute of Technology at the annual meeting of the American Physical Society. Richard Feynman suggested that it was possible to mechanically move single atoms with a manipulator of the appropriate size, at least such a process would not contradict the physical laws known today.

He suggested doing this manipulator in the following way. It is necessary to build a mechanism that would create its own copy, only an order of magnitude smaller. The created smaller mechanism must again create its copy, again an order of magnitude smaller, and so on until the dimensions of the mechanism are commensurate with the dimensions of the order of one atom. At the same time, it will be necessary to make changes in the structure of this mechanism, since the forces of gravity acting in the macrocosm will have less and less influence, and the forces of intermolecular interactions and van der Waals forces will increasingly affect the operation of the mechanism.

The last stage - the resulting mechanism will assemble its copy from individual atoms. In principle, the number of such copies is unlimited, it will be possible for a short time create an arbitrary number of such machines. These machines will be able to assemble macrothings in the same way, atom-by-atom assembly. This will make things an order of magnitude cheaper - such robots (nanorobots) will need to be given only the required number of molecules and energy, and write a program to assemble the necessary items. Until now, no one has been able to refute this possibility, but no one has yet managed to create such mechanisms. In the course of a theoretical study of this possibility, hypothetical doomsday scenarios have emerged that suggest that nanorobots will absorb the entire biomass of the Earth, carrying out their self-reproduction program (the so-called "gray goo" or "gray goo").

The first assumptions about the possibility of studying objects at the atomic level can be found in the book "Opticks" by Isaac Newton, published in 1704. In the book, Newton expresses the hope that the microscopes of the future will someday be able to explore "the mysteries of corpuscles."

The term "nanotechnology" was first used by Norio Taniguchi in 1974. He called this term the production of products with a size of several nanometers. In the 1980s, the term was used by Eric K. Drexler in his books Engines of Creation: The Coming Era of Nanotechnology and Nanosystems: Molecular Machinery, Manufacturing, and Computation.

What can nanotechnology do?

Here are just a few of the areas where nanotechnology promises breakthroughs:

The medicine

Nanosensors will ensure progress in the early diagnosis of diseases. This will increase the chances of recovery. We can beat cancer and other diseases. Old cancer drugs destroyed not only diseased cells, but also healthy ones. With the help of nanotechnology, the drug will be delivered directly to the diseased cell.

DNA nanotechnologies- use the specific bases of DNA molecules and nucleic acids to create clearly defined structures on their basis. Industrial synthesis of molecules of drugs and pharmacological preparations of a well-defined shape (bis-peptides).

In early 2000, thanks to the rapid progress in the technology of manufacturing nano-sized particles, an impetus was given to the development of a new field of nanotechnology - nanoplasmonics. It turned out to be possible to transmit electromagnetic radiation along a chain of metal nanoparticles by excitation of plasmon oscillations.

Construction

Nanosensors of building structures will monitor their strength, detect any threats to integrity. Objects built using nanotechnology can last up to five times longer than modern structures. Homes will adapt to the needs of residents, keeping them cool in summer and warm in winter.

Energy

We will be less dependent on oil and gas. Modern solar panels have an efficiency of about 20%. With the use of nanotechnology, it can grow by 2-3 times. Thin nanofilms on the roof and walls can provide energy to the whole house (if, of course, there is enough sun).

mechanical engineering

All bulky equipment will be replaced by robots - easily controlled devices. They will be able to create any mechanisms at the level of atoms and molecules. For the production of machines, new nanomaterials will be used that can reduce friction, protect parts from damage, and save energy. These are far from all the areas in which nanotechnologies can (and will!) be applied. Scientists believe that the emergence of nanotechnology is the beginning of a new scientific and technological revolution that will greatly change the world in the 21st century. However, it is worth noting that nanotechnologies do not enter the real practice very quickly. Not many devices (mostly electronics) work "with nano". This is partly due to the high cost of nanotechnology and the not very high return on nanotechnology products.

Probably, in the near future, with the help of nanotechnologies, high-tech, mobile, easily controlled devices will be created that will successfully replace the automated, but difficult to manage and bulky equipment of today. So, for example, over time, computer-controlled biorobots will be able to perform the functions of the current bulky pumping stations.

• DNA computer- a computing system that uses the computational capabilities of DNA molecules. Biomolecular computing is a collective name for various techniques related to DNA or RNA in one way or another. In DNA computing, data is not represented in the form of zeros and ones, but in the form of a molecular structure built on the basis of the DNA helix. Role software for reading, copying and managing data, special enzymes are performed.
• Atomic force microscope– scanning probe microscope high definition, based on the interaction of the cantilever tip (probe) with the surface of the sample under study. Unlike a scanning tunneling microscope (STM), it can examine both conductive and non-conductive surfaces even through a liquid layer, which makes it possible to work with organic molecules (DNA). The spatial resolution of an atomic force microscope depends on the size of the cantilever and the curvature of its tip. The resolution reaches atomic horizontally and significantly exceeds it vertically.
• Antenna oscillator- On February 9, 2005, an oscillator antenna with a size of about 1 micron was obtained in the laboratory of Boston University. This device has 5,000 million atoms and is capable of oscillating at a frequency of 1.49 gigahertz, which allows you to transfer huge amounts of information with it.

10 Nanotechnologies With Amazing Potential

Try to remember some canonical invention. Probably, someone now imagined a wheel, someone an airplane, and someone an iPod. And how many of you have thought about the invention of a completely new generation - nanotechnology? This world is little known, but it has incredible potential that can give us really fantastic things. The amazing thing is that the direction of nanotechnology did not exist until 1975, even though scientists began working in this area much earlier.

The human naked eye is able to recognize objects up to 0.1 mm in size. Today we will talk about ten inventions that are 100,000 times smaller.

Electrically conductive liquid metal

With electricity, a simple liquid metal alloy of gallium, iridium, and tin can be made to form complex shapes or wind circles inside a Petri dish. It can be said with some degree of probability that this is the material from which the famous T-1000 series cyborg was created, which we could see in Terminator 2.

“A soft alloy behaves like a smart form, capable of self-deforming if necessary, taking into account the changing surrounding space through which it moves. Just like a cyborg from a popular sci-fi movie could do, ”says Jin Li from Tsinghua University, one of the researchers involved in this project.

This metal is biomimetic, that is, it mimics biochemical reactions, although it is not itself a biological substance.

This metal can be controlled by electrical discharges. However, he himself is able to move independently, due to the emerging load imbalance, which is created by the difference in pressure between the front and back of each drop of this metal alloy. And although scientists believe that this process may be the key to converting chemical energy into mechanical energy, molecular material is not going to be used to build evil cyborgs in the near future. The whole process of "magic" can only take place in a sodium hydroxide solution or saline solution.

Nanoplasters

Researchers at the University of York are working to create special patches that will be designed to deliver all the necessary drugs into the body without any use of needles and syringes. Plasters of quite normal size are glued to the hand, delivering a certain dose of drug nanoparticles (small enough to penetrate through the hair follicles) inside your body. Nanoparticles (each less than 20 nanometers in size) will find harmful cells on their own, kill them and be removed from the body along with other cells as a result of natural processes.

Scientists note that in the future, such nanoplasters can be used in the fight against one of the most terrible diseases on Earth - cancer. Unlike chemotherapy, which in such cases is most often an integral part of the treatment, nanoplasters will be able to individually find and destroy cancer cells while leaving healthy cells intact. The nanopatch project was named NanJect. It is being developed by Atif Syed and Zakaria Hussain, who in 2013, while still students, received the necessary sponsorship as part of a crowdsourcing fundraising campaign.

Nanofilter for water

When this film is used in combination with a thin stainless steel mesh, the oil is repelled and the water in the area becomes pristine.

Interestingly, nature itself inspired scientists to create a nanofilm. Lotus leaves, also known as water lilies, have the opposite of nanofilms: instead of oil, they repel water. This is not the first time scientists have peeped at these amazing plants for their no less amazing properties. The result of this, for example, was the creation of superhydrophobic materials in 2003. As for the nanofilm, researchers are trying to create a material that mimics the surface of water lilies and enrich it with molecules of a special cleanser. The coating itself is invisible to the human eye. Production will be inexpensive: approximately $1 per square foot.

Submarine Air Purifier

It is unlikely that anyone thought about what kind of air the crews of submarines have to breathe, except for the crew members themselves. Meanwhile, the purification of air from carbon dioxide must be carried out immediately, since in one voyage through the light crews of the submarine the same air has to pass hundreds of times. To purify the air from carbon dioxide amines are used, which have a very unpleasant odor. To address this issue, a cleaning technology was created, called SAMMS (an acronym for Self-Assembled Monolayers on Mesoporous Supports). It proposes the use of special nanoparticles placed inside ceramic granules. The substance has a porous structure, due to which it absorbs excess carbon dioxide. The different types of SAMMS cleanings interact with different molecules in air, water, and earth, but all of these cleaning options are incredibly effective. Just one tablespoon of these porous ceramic granules is enough to clean an area equal to one football field.

Nanoconductors

Researchers at Northwestern University (USA) figured out how to create an electrical conductor at the nanoscale. This conductor is a hard and strong nanoparticle that can be tuned to transmit electric current in various opposite directions. The study shows that each such nanoparticle is able to emulate the operation of "a rectifier, switches and diodes." Each 5 nanometer-thick particle is coated with a positively charged chemical and surrounded by negatively charged atoms. Applying an electrical discharge reconfigures the negatively charged atoms around the nanoparticles.

The potential of the technology, according to scientists, is unprecedented. Based on it, you can create materials that "are capable of independently changing for certain computer computing tasks." The use of this nanomaterial will actually "reprogram" the electronics of the future. Hardware upgrades will be as easy as software upgrades.

Nanotech Charger

When this thing is created, you will no longer need to use any wired chargers. The new nanotechnology works like a sponge, only it absorbs non-liquid. She sucks out environment kinetic energy and sends it directly to your smartphone. The basis of the technology is the use of a piezoelectric material that generates electricity while in a state of mechanical stress. The material is endowed with nanoscopic pores that turn it into a flexible sponge.

The official name of this device is "nanogenerator". Such nanogenerators could one day become part of every smartphone on the planet, or part of the dashboard of every car, and perhaps even part of every pocket of clothing - gadgets will be charged right in it. In addition, the technology has the potential to be used at a larger scale, for example, in industrial equipment. At least that's what researchers at the University of Wisconsin-Madison think, who created this amazing nanosponge.

artificial retina

The Israeli company Nano Retina is developing an interface that will directly connect to the neurons of the eye and transmit the result of neural simulation to the brain, replacing the retina and returning people to sight.

An experiment on a blind chicken showed hope for the success of the project. The nanofilm allowed the chicken to see the light. True, the final stage of the development of an artificial retina to restore vision to people is still far away, but the progress in this direction cannot but rejoice. Nano Retina is not the only company involved in such developments, but it is their technology that is currently seen as the most promising, efficient and adaptive. The last point is the most important since we are talking about a product that will integrate into someone's eyes. Similar developments have shown that solid materials are unsuitable for such applications.

Since the technology is developed at the nanotechnological level, it eliminates the use of metal and wires, as well as avoiding the low resolution of the simulated image.

Glowing clothes

Shanghai scientists have developed reflective threads that can be used in the production of clothing. The basis of each thread is a very thin stainless steel wire, which is coated with special nanoparticles, a layer of electroluminescent polymer, and a protective sheath of transparent nanotubes. The result is very light and flexible threads that can glow under the influence of their own electrochemical energy. At the same time, they operate at much lower power than conventional LEDs.

The disadvantage of the technology lies in the fact that the “light reserve” of the threads is still enough for only a few hours. However, the developers of the material optimistically believe that they will be able to increase the "resource" of their product at least a thousand times. Even if they succeed, the solution to another drawback is still in question. Most likely, it will be impossible to wash clothes based on such nanothreads.

Nanoneedles for the restoration of internal organs

The nanoplasters we talked about above are designed specifically to replace needles. What if the needles themselves were only a few nanometers in size? In this case, they could change our understanding of surgery, or at least significantly improve it.

More recently, scientists have conducted successful laboratory tests on mice. With the help of tiny needles, researchers were able to inject nucleic acids into rodent organisms that promote the regeneration of organs and nerve cells and thereby restore lost performance. When the needles perform their function, they remain in the body and after a few days completely decompose in it. At the same time, scientists did not find any side effects during operations to restore the blood vessels of the muscles of the back of rodents using these special nanoneedles.

If we take into account human cases, then such nanoneedles can be used to deliver the necessary funds to the human body, for example, in organ transplantation. Special substances will prepare the surrounding tissues around the transplanted organ for rapid recovery and eliminate the possibility of rejection.

3D chemical printing

University of Illinois chemist Martin Burke is a real Willy Wonka from the world of chemistry. Using a collection of molecules of "building material" for various purposes, he can create a huge number of different chemical substances endowed with all sorts of "amazing and at the same time natural properties." For example, one such substance is ratanin, which can only be found in a very rare Peruvian flower.

The potential for synthesizing substances is so huge that it will make it possible to produce molecules used in medicine in the creation of LED diodes, solar cells and those chemical elements, the synthesis of which even the best chemists on the planet took years.

The capabilities of the current prototype of a three-dimensional chemical printer are still limited. He is able to create only new drugs. However, Burke hopes that one day he will be able to create a consumer version of his amazing device, which will have much more capabilities. It is quite possible that in the future such printers will act as a kind of home pharmacists.

Does nanotechnology pose a threat to human health or the environment?

There is not so much information about the negative impact of nanoparticles. In 2003, one study showed that carbon nanotubes could damage the lungs in mice and rats. A 2004 study showed that fullerenes can accumulate and cause brain damage in fish. But both studies used large doses of the substance under unusual conditions. According to one of the experts, chemist Kristen Kulinowski (USA), "it would be advisable to limit the impact of these nanoparticles, despite the fact that currently there is no information about their threat to human health."

Some commentators also argue that the widespread use of nanotechnology may lead to social and ethical risks. So, for example, if the use of nanotechnology initiates a new industrial revolution, it will lead to job losses. Moreover, nanotechnologies can change the idea of ​​a person, since their use will help prolong life and significantly increase the body's resistance. “No one can deny that the widespread use of mobile phones and the Internet has brought about enormous changes in society,” says Kristen Kulinowski. “Who dares to say that nanotechnology will not have a greater impact on society in the coming years?”

Place of Russia among the countries developing and producing nanotechnologies

The world leaders in terms of total investment in the field of nanotechnology are the EU countries, Japan and the United States. Recently, Russia, China, Brazil and India have significantly increased investments in this industry. In Russia, the amount of funding under the program "Development of nanoindustry infrastructure in Russian Federation for 2008-2010" will amount to 27.7 billion rubles.

In the latest (2008) report of the London-based research firm Cientifica, called the Nanotechnology Outlook Report, the following is written about Russian investments: “Although the EU still ranks first in terms of investment, China and Russia have already overtaken the United States.”

There are such areas in nanotechnology where Russian scientists became the first in the world, having obtained results that laid the foundation for the development of new scientific trends.

Among them are the production of ultrafine nanomaterials, the design of single-electron devices, as well as work in the field of atomic force and scanning probe microscopy. Only at a special exhibition held within the framework of the XII St. Petersburg Economic Forum (2008), 80 specific developments were presented at once. Russia already produces a number of nanoproducts that are in demand on the market: nanomembranes, nanopowders, nanotubes. However, according to experts, Russia is ten years behind the United States and other developed countries in the commercialization of nanotechnological developments.

Nanotechnology in art

A number of works by the American artist Natasha Vita-Mor deal with nanotechnological topics.

In contemporary art, a new direction "nanoart" (nanoart) has emerged - a type of art associated with the creation by the artist of sculptures (compositions) of micro- and nano-sizes (10 −6 and 10 −9 m, respectively) under the influence of chemical or physical processes of processing materials , photographing the obtained nano-images using an electron microscope and processing black-and-white photographs in a graphics editor.

In the well-known work of the Russian writer N. Leskov “Lefty” (1881), there is a curious fragment: “If,” he says, “there was a better small scope, which magnifies five million, so you would deign,” he says, “to see that on each horseshoe, the master's name is displayed: which Russian master made that horseshoe. An increase of 5,000,000 times is provided by modern electron and atomic force microscopes, which are considered the main tools of nanotechnology. In this way, literary hero Lefty can be considered the first "nanotechnologist" in history.

Feynman's 1959 lecture "There's a lot of room down there" on the ideas of how to create and use nanomanipulators coincide almost textually with the science fiction story "Microhands" by the famous Soviet writer Boris Zhitkov, published in 1931. Some of the negative consequences of the uncontrolled development of nanotechnologies are described in the works of M. Crichton ("Swarm"), S. Lem ("Inspection on the spot" and "Peace on Earth"), S. Lukyanenko ("Nothing to share").

The protagonist of the novel “Transman” by Y. Nikitin is the head of a nanotechnology corporation and the first person to experience the action of medical nanorobots.

In the sci-fi series Stargate SG-1 and Stargate Atlantis, one of the most technologically advanced races are two races of "replicators" that arose as a result of unsuccessful experiments with the use and description of various applications of nanotechnology. In the film The Day the Earth Stood Still, starring Keanu Reeves, an alien civilization passes a death sentence on humanity and almost destroys everything on the planet with the help of self-replicating nano-replicant beetles, devouring everything in its path.

MOU "Humanities and Pedagogical Lyceum"

Nanotechnology for schoolchildren

Completed by: Sagaydachnaya Anastasia, 10 "B" class

Introduction__________________________________________________________________3

History of nanotechnology __________________________________________________________4

Nanotechnology tools________________________________________________10

Mysteries of the nanoworld _______________________________________________________________25

Nanotechnology and medicine__________________________________________________36

Nanotechnologies in everyday life and industry ___________________________________42

For those who want to connect the future with nanotechnology ___________________________52

References __________________________________________________________________________56

Introduction

Airplanes, rockets, televisions and computers have changed the world in the 20th century. Scientists argue that in the coming 21st century, the core of a new technological revolution will be materials, medicines, devices, communication and delivery systems made using nanotechnology.

Translated from Greek, the word "nano" means dwarf. One nanometer (nm) is one billionth of a meter (10 -9 m). A nanometer is very, very small. A nanometer is as many times less than one meter as the thickness of a finger is less than the diameter of the Earth. Most atoms are between 0.1 and 0.2 nm in diameter, and DNA strands are about 2 nm thick. The diameter of red blood cells is 7000 nm, and the thickness of a human hair is 80,000 nm.

Before our eyes, fantasy becomes a reality - it becomes possible to move individual atoms and put them together, like from cubes, devices and mechanisms of unusually small sizes and therefore invisible to the ordinary eye. Nanotechnology, using the latest achievements in physics, chemistry and biology, is not just a quantitative, but a qualitative leap from working with matter to manipulating individual atoms.

The history of the emergence and development of nanotechnology

Richard Feynman - Prophet of the Nanotechnology Revolution

The idea that it is quite possible to assemble devices and work with objects that are nanoscale was first expressed in the speech of the laureate Nobel Prize Richard Feynman in 1959 at the California Institute of Technology ("There's plenty of room down there!"). The word "below" in the title of the lecture meant in "a very small world." Then Feynman said that someday, for example, in the year 2000, people will wonder why scientists in the first half of the 19th century jumped this nanoscale size range, concentrating all their efforts on the study of the atom and the atomic nucleus. According to Feynman, people lived for a very long time, not noticing that a whole world of objects lives next to them, which it was impossible to see. Well, if we did not see these objects, then we could not work with them.

However, we ourselves are made up of devices that have learned how to work with nano-objects perfectly. These are our cells - the bricks that make up our body. The cell all its life works with nano-objects, assembling molecules of complex substances from various atoms. Having assembled these molecules, the cell places them in different parts - some end up in the nucleus, others in the cytoplasm, and still others in the membrane. Imagine the possibilities that open up before humanity if it masters the same nanotechnologies that every human cell already owns.

Feynman describes the implications of the nanotechnology revolution for computers in this way. “If, for example, the diameter of the connecting wires will be from 10 to 100 atoms, then the size of any circuit will not exceed several thousand angstroms. Everyone who is connected with computer technology knows about the possibilities that its development and complication promises. If the number of elements used increases millions of times, then the capabilities of computers will expand significantly. They will learn to reason, analyze experience and calculate their own actions, find new computational methods, etc. An increase in the number of elements will lead to important qualitative changes in the characteristics of the computer.”

Calling scientists to the nanoworld, Feynman immediately warns of the obstacles that await them there, using the example of manufacturing a microcar only 1 mm long. Since the parts of an ordinary car are made with an accuracy of 10 -5 m, the parts of a microcar should be made with an accuracy 4000 times higher, i.e. 2.5. 10 -9 m. Thus, the dimensions of the microcar parts must correspond to the calculated ones with an accuracy of ± 10 layers of atoms.

The nanoworld is not only full of obstacles and problems. Good news awaits us in the nanoworld - all the details of the nanoworld turn out to be very durable. This happens due to the fact that the mass of nano-objects decreases in proportion to the third power of their size, and their cross-sectional area decreases in proportion to the second power. This means that the mechanical load on each element of the object - the ratio of the weight of the element to its cross-sectional area - decreases in proportion to the size of the object. Thus, a proportionally reduced nanotable has a billion times thicker nanolegs than necessary.

F Einman believed that a person could easily master the nanoworld if he created a robotic machine capable of making a reduced but workable copy of himself. Let, for example, we have learned how to make a robot that can create its copy reduced by 4 times without our participation. Then this small robot will be able to make a copy of the original one, reduced by 16 times, and so on. Obviously, the 10th generation of such robots will create robots that will be millions of times smaller than the original ones (see Fig. 3).

Figure 3. Illustration of the concept of R. Feynman, who proposed one of the algorithms for how one could enter the nanoworld - robots autonomously make their reduced copies. Adapted from Scientific American, 2001, Sept., p. 84.

Of course, as we decrease in size, we will constantly encounter very unusual physical phenomena. The negligible weight of the parts of the nanorobot will lead to the fact that they will stick to each other under the action of intermolecular forces, and, for example, the nut will not separate from the bolt after unscrewing. However, the laws of physics known to us do not prohibit the creation of objects “atom by atom”. The manipulation of atoms is, in principle, quite real and does not violate any laws of nature. The practical difficulties of its implementation are due only to the fact that we ourselves are too large and bulky objects, as a result of which it is difficult for us to carry out such manipulations.

In order to somehow stimulate the creation of micro-objects, Feynman promised to pay $ 1,000 to someone who would build a 1/64-inch electric motor (1 inch » 2.5 cm). And very soon such a micromotor was created (see Fig. 4). Since 1993, the Feynman Prize has been awarded annually for outstanding achievements in the field of nanotechnology.

Figure 4. In the photo (a), R. Feynman (right) examines with a microscope the made micromotor, 380 microns in size, shown in the figure on the right. The top photo (b) shows the head of a pin.

In his lecture, Feynman spoke about the prospects of nanochemistry. Chemists now use complex and varied methods to synthesize new substances. Once physicists create devices capable of handling individual atoms, many of the methods of traditional chemical synthesis can be replaced by "atomic assembly" techniques. At the same time, as Feynman believed, physicists, in principle, can really learn to synthesize any substance, based on the written chemical formula. Chemists will order the synthesis, and physicists will simply "stack" the atoms in the proposed order. The development of manipulation techniques at the atomic level will solve many problems of chemistry and biology.

E. Drexler's machines of creation

Nanotechnology emerged as a field of science in its own right and evolved into a long-term technical project following a detailed analysis by the American scientist Eric Drexler in the early 1980s and the publication of his book Machines of Creation: The Coming Era of Nanotechnology.

This is how his book begins. “COAL AND DIAMONDS, sand and computer chips, cancer and healthy tissue - throughout history, depending on the ordering of atoms, cheap or precious, sick or healthy appeared. Ordered in the same way, the atoms make up soil, air, and water; ordered by others, they make up ripe strawberries. Ordered in one way, they form houses and fresh air; ordered by others, they form ash and smoke.

Our ability to arrange atoms is at the heart of technology. We have come a long way in our ability to arrange atoms, from sharpening flint for arrowheads to working aluminum for spaceships. We are proud of our technology, our life-saving medicines and desktop computers. However, our spaceships are still crude, our computers are still stupid, and the molecules in our tissues are still gradually becoming disordered, first destroying health and then life itself. For all our success in ordering atoms, we still use primitive methods of ordering. With our current technology, we are still forced to manipulate large, poorly controlled groups of atoms.

But the laws of nature provide many opportunities for progress, and the pressure of world competition is always pushing us forward. For better or worse, the greatest technological achievement in history lies ahead of us.”

According to Drexler, nanotechnology is "an expected production technology focused on the cheap production of devices and substances with a predetermined atomic structure." Within the next 50 years, many experts believe that many devices will become so small that a thousand such nanomachines could easily fit into the area occupied by the dot at the end of this sentence. To collect nanomachines, you need:

(1) learn how to work with single atoms - take them and put them in the right place.

(2) to develop assemblers (nanodevices) that could work with single atoms as explained in (1), according to programs written by a person, but without his participation. Since each manipulation with an atom requires a certain amount of time, and there are a lot of atoms, according to scientists, it is necessary to make billions or even trillions of such nanoassemblies so that the assembly process does not take much time.

(3) to develop replicators - devices that would be manufactured by nanoassemblers, since they will have to make a lot, a lot.

It will be years before nano-assemblers and replicators appear, but their appearance seems almost inevitable. At the same time, each step along the way will make the next one more real. The first steps towards the creation of nanomachines have already been made. These are "genetic engineering" and "biotechnology".

Healing Machines

E. Drexler suggested using nanomachines for human treatment. The human body is made of molecules, and people become sick and old because "unnecessary" molecules appear, and the concentration of "necessary" decreases or their structure changes. As a result, people suffer. Nothing prevents a person from inventing nanomachines capable of reordering atoms in “spoiled” molecules or reassembling them. It is clear that such nanomachines could revolutionize medicine.

In the future, nanomachines (nanorobots) will be created, adapted to penetrate into a living cell, analyze its state and, if necessary, “treat” it by changing the structure of the molecules that make it up. These cell-repairing nanomachines will be comparable in size to bacteria and will move through human tissues as leukocytes (white blood cells) do and enter cells as viruses do (see Figure 6).

With the creation of nanomachines for cell repair, the treatment of a patient will turn into a sequence of the following operations. First, working out molecule by molecule and structure by structure, nanomachines will restore (heal) cell by cell of any tissue or organ. Then, working out organ after organ throughout the body, they will restore the health of a person.

Figure 6. Schematic representation of the nanorobot on the cell surface. It can be seen how the tentacles of the nanorobot penetrated the cell.

Photolithography - the road to the nanoworld: from top to bottom

Scientists and technologists have long been striving for a world of small sizes, especially those who develop new electronic devices and devices. For an electronic device to be smart and reliable, it must consist of a huge number of blocks, and therefore contain thousands, and sometimes millions of transistors.

In the manufacture of transistors and integrated circuits, optical photolithography is used. Its essence is as follows. A layer of photoresist (polymeric light-sensitive material) is applied to the oxidized silicon surface, and then a photomask is superimposed on it - a glass plate with a pattern of integrated circuit elements (see Fig. 7).

Figure 7. Photomask for an integrated circuit of an electronic clock.

The beam of light passes through the photomask, and where there is no black color, the light hits the photoresist and illuminates it (see Fig. 8).

Figure 8. Scheme of fabrication of microcircuits using photolithography (from left to right). First, a photomask is made, for which a glass plate coated with a layer of chromium and photoresist is illuminated with a laser beam, and then the illuminated parts of the photoresist are removed along with chromium. The template is placed in a parallel beam of ultraviolet light, which is focused by a lens and incident on the surface of a silicon wafer coated with a thin layer of silicon oxide and photoresist. Subsequent thermal and chemical treatments create the complex two-dimensional pattern of grooves needed to assemble an electronic circuit.

After that, all those areas of the photoresist that were not treated with light are removed, and those that were illuminated are subjected to heat treatment and chemical etching. Thus, a pattern is formed on the surface of the silicon oxide, and the silicon wafer is ready to become the main part of the electronic circuit. The transistor was invented in 1947, and then its dimensions were about 1 cm. Improvement in photolithographic methods made it possible to bring the size of the transistor to 100 nm. However, the basis of photolithography is geometric optics, which means that using this method it is impossible to draw two parallel straight lines at a distance less than a wavelength. Therefore, short wavelength ultraviolet is currently used in photolithographic fabrication of microcircuits, but it becomes expensive and difficult to further reduce the wavelength, although modern technologies already use electron beams to create microcircuits.

The introduction into the world of nanoscale, which has been followed by chip manufacturers so far, can be called a “top-down” road. They use technologies that have proven themselves in the macro world, and only try to change the scale. But there is another way - "from the bottom up". But what if we force the atoms and molecules themselves to self-organize into ordered groups and structures a few nanometers in size? Examples of self-organization of molecules that form nanostructures are carbon nanotubes, quantum dots, nanowires and dendrimers, which will be discussed in more detail below.

NANOTECHNOLOGY TOOLS

Scanning probe microscope

The first devices that made it possible to observe nano-objects and move them were scanning probe microscopes - an atomic force microscope and a scanning tunneling microscope operating on a similar principle. Atomic force microscopy (AFM) was developed by G. Binnig and G. Rohrer, who were awarded the Nobel Prize in 1986 for these studies. The creation of an atomic force microscope, capable of feeling the forces of attraction and repulsion that arise between individual atoms, made it possible, finally, to "feel and see" nano-objects.

Figure 9. The principle of operation of a scanning probe microscope. The dotted line shows the path of the laser beam. Other explanations in the text.

The basis of the AFM (see Fig. 9) is a probe, usually made of silicon and representing a thin plate-console (it is called a cantilever, from the English word "cantilever" - console, beam). At the end of the cantilever (length  500 µm, width  50 µm, thickness  1 µm) there is a very sharp spike (length  10 µm, curvature radius from 1 to 10 nm), ending in a group of one or more atoms (see Fig. ten).

Figure 10. Electron microphotographs of the same probe taken at low (top) and high magnification.

As the microprobe moves along the sample surface, the tip of the spike rises and falls, outlining the microrelief of the surface, just as a gramophone needle slides over a gramophone record. At the protruding end of the cantilever (above the spike, see Fig. 9) there is a mirror area, on which the laser beam falls and is reflected. As the spike descends and rises on uneven surfaces, the reflected beam is deflected, and this deflection is recorded by a photodetector, and the force with which the spike is attracted to nearby atoms is recorded by a piezoelectric sensor.

The data from the photodetector and the piezoelectric sensor are used in a feedback system that can provide, for example, a constant value of the interaction force between the microprobe and the sample surface. As a result, it is possible to build a three-dimensional relief of the sample surface in real time. The resolution of the AFM method is approximately 0.1-1 nm horizontally and 0.01 nm vertically. An image of the bacterium Escherichia coli obtained using a scanning probe microscope is shown in fig. eleven.

Figure 11. E. coli bacterium ( Escherichia coli). The image was obtained using a scanning probe microscope. The bacterium is 1.9 µm long and 1 µm wide. The thickness of flagella and cilia is 30 nm and 20 nm, respectively.

Another group of scanning probe microscopes uses the so-called quantum-mechanical "tunnel effect" to build the surface topography. The essence of the tunnel effect is that the electric current between a sharp metal needle and a surface located at a distance of about 1 nm begins to depend on this distance - the smaller the distance, the greater the current. If a voltage of 10 V is applied between the needle and the surface, then this "tunneling" current can be from 10 pA to 10 nA. By measuring this current and keeping it constant, the distance between the needle and the surface can also be kept constant. This allows you to build a three-dimensional surface profile (see Fig. 12). Unlike an atomic force microscope, a scanning tunneling microscope can only study the surfaces of metals or semiconductors.

Figure 12. The needle of a scanning tunneling microscope, located at a constant distance (see arrows) above the layers of atoms of the surface under study.

A scanning tunneling microscope can also be used to move an atom to a point chosen by the operator. For example, if the voltage between the microscope tip and the surface of the sample is made somewhat greater than necessary to study this surface, then the sample atom closest to it turns into an ion and "jumps" onto the needle. After that, by slightly moving the needle and changing the voltage, the escaped atom can be made to "jump" back to the surface of the sample. Thus, it is possible to manipulate atoms and create nanostructures, i.e. structures on the surface, having dimensions of the order of a nanometer. Back in 1990, IBM employees showed that this was possible by adding up the name of their company on a nickel plate from 35 xenon atoms (see Fig. 13).

Figure 13. 35 xenon atoms on a nickel plate, the name of the company IBM, made by employees of this company using a scanning probe microscope in 1990.

Using a probe microscope, one can not only move atoms, but also create prerequisites for their self-organization. For example, if there is a drop of water containing thiol ions on a metal plate, then the microscope probe will promote such an orientation of these molecules, in which their two hydrocarbon tails will be turned away from the plate. As a result, it is possible to build up a monolayer of thiol molecules adhering to the metal plate (see Fig. 14). This method of creating a monolayer of molecules on a metal surface is called "pen nanolithography".

Figure 14. Top left - cantilever (grey-steel) of a scanning probe microscope above a metal plate. On the right is a magnified image of the area (circled in white in the figure on the left) under the cantilever probe, which schematically shows thiol molecules with purple hydrocarbon tails lining up in a monolayer at the tip of the probe.

Optical tweezers

An optical (or laser) tweezer is a device that uses a focused laser beam to move microscopic objects or hold them in place. Near the focal point of the laser beam, the light pulls everything that is around to the focus (see Fig. 15).

Figure 15. Schematic representation of an optical tweezer. The laser beam incident on the lens from above is focused inside the drop. At the same time, forces (orange arrows) act on each particle in the water, the resultant of which (green arrow) is always directed towards the focus.

The force with which the light acts on the surrounding objects is small, but it turns out to be enough to catch the nanoparticles in the focus of the laser beam. Once the particle is in focus, it can be moved along with the laser beam. Using optical tweezers, particles ranging in size from 10 nm to 10 µm can be moved and various structures can be assembled from them (see Fig. 16). There is every reason to believe that in the future laser tweezers will become one of the most powerful nanotechnology tools.

Figure 16. Different patterns of gel nanoparticles folded with laser tweezers.

Why do some particles, being in a laser beam, tend to the area where the light intensity is maximum, i.e. into focus (see Fig. 17)? There are at least TWO reasons for this.

Figure 17. Schematic representation of a red beam converging towards the focus and diverging after it. A gray spherical particle is visible at the point where the beam is focused.

CauseI - polarized particles are drawn into the electric field

Before explaining the tendency of particles to focus, remember that a beam of light is an electromagnetic wave, and the greater the intensity of the light, the greater the electric field strength in the cross section of the beam. Therefore, at the focus, the root-mean-square value of the electric field strength can increase many times over. Thus, the electric field of the focused light beam becomes non-uniform, increasing in intensity as it approaches the focus.

Let the particle that we want to hold with the help of optical tweezers is made of a dielectric. It is known that an external electric field acts on a dielectric molecule, moving opposite charges inside it in different directions, as a result of which this molecule becomes a dipole, which is oriented along the field lines of force. This phenomenon is called polarization dielectric. When a dielectric is polarized, on its opposite surfaces with respect to the external field, opposite and equal electric charges appear, called related.

Figure 18. Schematic representation of a spherical particle in a HOMOGENEOUS electric field with strength E. The signs "+" and "-" show the bound charges that have arisen on the surface of the particle during its polarization. The electrical forces acting on positive (F+) and negative (F-) bound charges are the same.

Let our dielectric particle be in the light beam away from the focus. Then we can assume that it is in a uniform electric field (see Fig. 18). Since the electric field strength to the left and right of the particle is the same, then the electric forces acting on the positive ( F+) and negative ( F-) associated charges are also the same. As a result, a particle in a HOMOGENEOUS electric field remains STILL.

Now let our particle be near the focus area, where the electric field strength (density of field lines) gradually increases (the leftmost particle in Fig. 19) as it moves from left to right. At this point, the particle will also be polarized, but the electric forces acting on the positive ( F+) and negative ( F-) related charges will be different, because the field strength to the left of the particle is less than to the right. Therefore, the resulting force will act on the particle, directed to the right, towards the focus area.

Figure 19. Schematic representation of THREE spherical particles in a non-uniform electric field of a focused light beam near the focus area. The "+" and "-" signs show the bound charges that appeared on the surface of the particles during their polarization. Electrical forces acting on positive (F+) and negative (F-) bound charges cause particles to move towards the focus area.

It is easy to guess that the far right particle (see Fig. 19), located on the other side of the focus, will be affected by the resultant particle directed to the left, towards the focus area. Thus, all particles that find themselves in a focused beam of light will tend to its focus, as a pendulum tends to the equilibrium position.

CauseII - refraction of light keeps the particle in the center of the beam

If the particle diameter is much larger than the wavelength of light, then the laws of geometric optics become valid for such a particle, namely, the particle can refract light, i.e. change its direction. At the same time, according to the law of conservation of momentum, the sum of the momenta of light (photons) and the particle must remain constant. In other words, if a particle refracts light, for example, to the right, then it itself must move to the left.

It should be noted that the intensity of light in a laser beam is maximum along its axis and gradually decreases with distance from it. Therefore, if the particle is on the axis of the light beam, then the number of photons deflected by it to the left and to the right is the same. As a result, the particle remains on the axis (see Fig. 20 b).

Figure 20. Schematic representation of a spherical particle located in a focused beam of light to the left of its axis (a) and on its axis (b). The intensity of red shading corresponds to the intensity of light in a given area of ​​the beam. 1 and 2 - rays, the refraction of which is shown in the figure, and the thickness corresponds to their intensity. F 1 and F 2 - forces acting on the particle according to the law of conservation of momentum, when beams 1 and 2 are refracted, respectively. F net - resulting F 1 and F 2 .

In cases where the particle is shifted to the left relative to the axis of the light beam (see Fig. 20a), the number of photons deflected to the left (see beam 2 in Fig. 20a) exceeds their number deflected to the right (see beam 1 in Fig. 20a). ). Therefore, there is a component of the force F net , directed to the axis of the beam, to the right.

It is obvious that the particle shifted to the right of the beam axis will be affected by the resultant particle directed to the left, and again to the axis of this beam. Thus, all particles that are not on the axis of the beam will tend to its axis, like a pendulum to the equilibrium position.

Exceptions to the rules

For the optical tweezers to use the forces described above in "cause I", it is necessary that the particle be polarized in an external electric field, and bound charges appear on its surface. In this case, the bound charges must create a field directed in the opposite direction. Only in this case, the particles will rush to the focus region. If the dielectric constant of the medium, in which the particle floats is greater than the dielectric constant of the particle's substance, then the polarization of the particle will be reversed, and the particle will tend to escape from the focus area.For example, air bubbles floating in glycerin behave like this.

The same restrictions apply to the "cause II". If the absolute refractive index of the particle's materials is less than that of the medium in which it is located, then the particle will deflect light in the other direction, and therefore tend to move away from the beam axis. An example would be the same air bubbles in glycerin. Therefore optical tweezers work better if the relative refractive index of the particle material is larger.

Graphene, carbon nanotubes and fullerenes

Nanostructures can be assembled not only from individual atoms or single molecules, but molecular blocks. Such blocks or elements for creating nanostructures are graphene, carbon nanotubes and fullerenes.

Graphene

Graphene is a single flat sheet consisting of carbon atoms linked together and forming a lattice, each cell of which resembles a honeycomb (Fig. 21). The distance between the nearest carbon atoms in graphene is about 0.14 nm.

Figure 21. Schematic representation of graphene. The light balls are carbon atoms, and the rods between them are the bonds that hold the atoms in the graphene sheet.

Graphite, from which the leads of ordinary pencils are made, is a stack of sheets of graphene (Fig. 22). The graphenes in graphite are very poorly bonded and can slide relative to each other. Therefore, if graphite is drawn over paper, then the graphene sheet in contact with it is separated from the graphite and remains on the paper. This explains why graphite can be written.

Figure 22. Schematic representation of three graphene sheets stacked on top of each other in graphite.

carbon nanotubes

Many promising areas in nanotechnology are associated with carbon nanotubes. Carbon nanotubes are framework structures or giant molecules consisting only of carbon atoms. It is easy to imagine a carbon nanotube if you imagine that you roll one of the molecular layers of graphite, graphene, into a tube (Fig. 23).

Figure 23. One of the imaginary ways to fabricate a nanotube (right) from a molecular layer of graphite (left).

The way nanotubes are folded, i.e., the angle between the direction of the nanotube axis with respect to the symmetry axes of graphene (twist angle), largely determines its properties. Of course, no one makes nanotubes by rolling them from a sheet of graphite. Nanotubes are formed by themselves, for example, on the surface of carbon electrodes during an arc discharge between them. During the discharge, carbon atoms evaporate from the surface and, connecting with each other, form nanotubes of various types - single-layer, multilayer, and with different twist angles (Fig. 24).

Figure 24. Left - schematic representation of a single-layer carbon nanotube; on the right (from top to bottom) - two-layer, straight and spiral nanotubes.

The diameter of single-walled nanotubes, as a rule, is about 1 nm, and their length is thousands of times greater, amounting to about 40 microns. They grow on the cathode perpendicular to the flat surface of its end. The so-called self-assembly of carbon nanotubes from carbon atoms takes place. Depending on the angle of twist, nanotubes can have high conductivity, like that of metals, or they can have the properties of semiconductors.

Carbon nanotubes are stronger than graphite, although they are made of the same carbon atoms, because in graphite the carbon atoms are in sheets (Fig. 22). And everyone knows that a sheet of paper folded into a tube is much more difficult to bend and tear than a regular sheet. This is why carbon nanotubes are so strong. Nanotubes can be used as very strong microscopic rods and threads, because the Young's modulus of a single-layer nanotube reaches values ​​of the order of 1-5 TPa, which is an order of magnitude greater than that of steel! Therefore, a thread made of nanotubes, as thick as a human hair, is capable of holding a load of hundreds of kilograms.

True, at present, the maximum length of nanotubes is usually about a hundred microns - which, of course, is too short for everyday use. However, the length of nanotubes obtained in the laboratory is gradually increasing - now scientists have already come close to the millimeter limit. Therefore, there is every reason to hope that in the near future, scientists will learn how to grow nanotubes that are centimeters and even meters long!

Fullerenes

Carbon atoms evaporated from the heated surface of graphite, connecting with each other, can form not only nanotubes, but also other molecules that are convex closed polyhedra, for example, in the form of a sphere or an ellipsoid. In these molecules, carbon atoms are located at the vertices of regular hexagons and pentagons, which make up the surface of a sphere or ellipsoid.

All these molecular compounds of carbon atoms are named fullerenes named after the American engineer, designer and architect R. Buckminster Fuller, who used five- and hexagons (Fig. 25), which are the main structural elements of the molecular frameworks of all fullerenes, to construct the domes of his buildings.

Figure 25. Fuller Biosphere (US Pavilion at Expo 67, now the Biosphere Museum in Monreale, Canada.

Molecules of the most symmetrical and most studied fullerene, consisting of 60 carbon atoms (C 60), form polyhedron, consisting of 20 hexagons and 12 pentagons and resembling a soccer ball (Fig. 26). The diameter of fullerene C 60 is about 1 nm.

Figure 26. Schematic representation of C 60 fullerene.

For the discovery of fullerenes to the American physicist R. Smalley, as well as to the English physicists H. Kroto and R. Curl in 1996 was awarded Nobel Prize. Image of fullerene C 60 is considered by many to be a symbol of nanotechnology.

Dendrimers

One of the elements of the nanoworld are dendrimers (tree-like polymers) - nanostructures ranging in size from 1 to 10 nm, formed by the combination of molecules with a branching structure. The synthesis of dendrimers is one of the nanotechnologies that is closely related to chemistry - the chemistry of polymers. Like all polymers, dendrimers are made up of monomers, but the molecules of these monomers have a branched structure. A dendrimer becomes similar to a tree with a spherical crown if, during the growth of the polymer molecule, the growing branches do not join (just as the branches of one tree, or the crowns of adjacent trees do not grow together). Figure 27 shows how such spherical-like dendrimers can form.

Figure 27. Assembly of a dendrimer from a Z-X-Z branching molecule (top) and different types of dendrimers (bottom).

Cavities filled with the substance in the presence of which the dendrimers were formed can form inside the dendrimer. If a dendrimer is synthesized in a solution containing a drug, then this dendrimer becomes a nanocapsule with this drug. In addition, the cavities within the dendrimer may contain radioactively labeled substances used to diagnose various diseases.

Scientists believe that by filling the cavities of dendrimers with the necessary substances, it is possible, for example, using a scanning probe microscope, to assemble nanoelectronic circuits from various dendrimers. In this case, a dendrimer filled with copper could serve as a conductor, etc.

Of course, a promising direction in the application of dendrimers is their possible use as nanocapsules delivering drugs directly to cells in need of these drugs. The central part of such dendrimers, containing the drug, should be surrounded by a shell that prevents leakage of the drug, to the outer surface of which it is necessary to attach molecules (antibodies) that can stick precisely to the surface of the target cells. As soon as such nanocapsules-dendrimers reach and adhere to diseased cells, it is necessary to destroy the outer shell of the dendrimer, for example, with a laser, or make this shell self-decomposing.

Dendrimers are one of the paths to the nanoworld in the "bottom-up" direction.

nanowires

Nanowires are called wires with a diameter of the order of a nanometer, made of metal, semiconductor or dielectric. The length of nanowires can often exceed their diameter by a factor of 1000 or more. Therefore, nanowires are often called one-dimensional structures, and their extremely small diameter (about 100 atom sizes) makes it possible to manifest various quantum mechanical effects. This explains why nanowires are sometimes referred to as "quantum wires".

Nanowires do not exist in nature. In laboratories, nanowires are most often obtained by the method epitaxy when the crystallization of a substance occurs in only one direction. For example, a silicon nanowire can be grown as shown in the figure (left).

Figure 28. On the left is the preparation of a silicon nanowire (pink) by epitaxy using a gold nanoparticle in an SiH 4 atmosphere. On the right is a “forest” of ZnO nanowires obtained by epitaxy. Adapted from Yang et al. (Chem. Eur. J., v.8, p.6, 2002)

A gold nanoparticle is placed in an atmosphere of silane gas (SiH 4), and this nanoparticle becomes a catalyst for the reaction of silane decomposition into hydrogen and liquid silicon. Liquid silicon rolls off the nanoparticle and crystallizes under it. If the silane concentration around the nanoparticle is maintained unchanged, then the epitaxy process continues, and more and more layers of liquid silicon crystallize on its already solidified layers. As a result, the silicon nanowire grows, lifting the gold nanoparticle higher and higher. In this case, obviously, the size of the nanoparticle determines the diameter of the nanowire. On the right in fig. 28 shows a forest of ZnO nanowires prepared in a similar manner.

The unique electrical and mechanical properties of nanowires create prerequisites for their use in future nanoelectronic and nanoelectromechanical devices, as well as elements of new composite materials and biosensors.

MYSTERIES OF THE NANO WORLD

Friction under the microscope

We encounter friction at every step, but without friction we would not even take a step. It is impossible to imagine a world without friction forces. In the absence of friction, many short-term motions would continue indefinitely. The earth would shake from continuous earthquakes, as the tectonic plates were constantly colliding with each other. All glaciers would immediately roll down from the mountains, and the dust from last year's wind would rush over the surface of the earth. It's good that there is still a force of friction in the world!

On the other hand, friction between machine parts leads to wear and tear and additional costs. Rough estimates show that scientific research in tribology - the science of friction - could save about 2 to 10% of the national gross product.

The two most important inventions of man - the wheel and making fire - are associated with the force of friction. The invention of the wheel made it possible to significantly reduce the force that impedes movement, and the making of fire put the force of friction at the service of man. However, until now, scientists are far from a complete understanding of the physical foundations of the friction force. And not at all because people have ceased to be interested in this phenomenon for some time now.

The first formulation of the laws of friction belongs to the great Leonardo (1519), who argued that the friction force arising from the contact of a body with the surface of another body is proportional to the pressing force, directed against the direction of motion and does not depend on the contact area. This law was rediscovered 180 years later by G. Amonton, and then refined in the works of S. Coulomb (1781). Amonton and Coulomb introduced the concept of the friction coefficient as the ratio of the friction force to the load, giving it the value of a physical constant that completely determines the friction force for any pair of contacting materials. So far, this formula

F tr = μ N, (1)

where F tr - friction force, N- the component of the pressing force, normal to the contact surface, and μ - the coefficient of friction, is the only formula that can be found in school textbooks in physics (see Fig. 29).

Figure 29. To the formulation of the classical law of friction.

For two centuries, no one has been able to refute the experimentally proven law (1), and so far it sounds like it did 200 years ago:

 The friction force is directly proportional to the normal component of the force compressing the surface of the sliding bodies, and always acts in the direction opposite to the direction of motion.

 The force of friction does not depend on the size of the contact surface.

 The force of friction does not depend on the speed of sliding.

The static friction force is always greater than the sliding friction force.

 Friction forces depend only on two materials that slide over each other.

Is the classical law of friction always valid?

Already in the 19th century, it became clear that the Amonton-Coulomb law (1) does not always correctly describe the friction force, and friction coefficients are by no means universal characteristics. First of all, it was noted that the coefficients of friction depend not only on what materials are in contact, but also on how smoothly the contact surfaces are processed. It turned out, for example, that the coefficients of friction in a vacuum are always greater than under normal conditions (see table below).

Commenting on these discrepancies, the Nobel Prize winner in physics R. Feynman wrote in his lectures - ... The tables listing the coefficients of friction "steel on steel", "copper on copper" and so on, all this is a complete swindle, because these little things are neglected in them, but they determine the value of μ. Friction "copper on copper", etc. - this is actually friction "about pollution adhering to copper".

You can, of course, go the other way and, by studying the friction of "copper on copper", measure the forces during the movement of perfectly polished and degassed surfaces in a vacuum. But then two such pieces of copper will simply stick together, and the coefficient of static friction will begin to grow with the time that has passed since the beginning of the contact of the surfaces. For the same reasons, the coefficient of sliding friction will depend on the speed (increase with its decrease). This means that it is also impossible to accurately determine the friction force for pure metals.

However, for dry standard surfaces, the classical law of friction is almost exact, although the reason for this type of law remained unclear until very recently. After all, no one could theoretically estimate the coefficient of friction between two surfaces.

How do atoms rub against each other?

The difficulty of studying friction lies in the fact that the place where this process takes place is hidden from the researcher from all sides. Despite this, scientists have long concluded that the force of friction is due to the fact that at the microscopic level (ie, when viewed through a microscope) the contacting surfaces are very rough even if they have been polished. Therefore, the sliding of two surfaces over each other may resemble a fantastic case when the inverted Caucasus Mountains rub against, for example, the Himalayas (Fig. 30).

Figure 30. Schematic representation of the contact point of sliding surfaces with a small (top) and large (bottom) compressing force.

Previously, it was thought that the mechanism of friction is simple: the surface is covered with irregularities, and friction is the result of successive “rise-lower” cycles of sliding parts. But this is wrong, because then there would be no energy loss, and friction consumes energy.

The following model of friction can be considered closer to reality. When rubbing surfaces slide, their microroughnesses come into contact, and at the points of contact, the atoms opposing each other are attracted to each other, as it were, "linked". With further relative motion of the bodies, these couplings are torn, and vibrations of atoms arise, similar to those that occur when a stretched spring is released. Over time, these vibrations fade, and their energy turns into heat, spreading over both bodies. In the case of sliding soft bodies, it is also possible to destroy microroughnesses, the so-called "ploughing", in this case, mechanical energy is spent on the destruction of intermolecular or interatomic bonds.

Thus, if we want to study friction, we must contrive to move a grain of sand, consisting of several atoms, along the surface at a very small distance from it, while measuring the forces acting on this grain of sand from the surface. This became possible only after the invention of atomic force microscopy. The creation of an atomic force microscope (AFM), capable of feeling the forces of attraction and repulsion that arise between individual atoms, made it possible, finally, to “feel” what friction forces are, opening up a new area of ​​friction science - nanotribology.

Since the early 1990s, AFM has been used to systematically study the friction force of microprobes as they slide along various surfaces and the dependence of these forces on the pressing force. It turned out that for commonly used probes made of silicon, the microscopic sliding friction force is about 60-80% of the pressing force, which is no more than 10 nN (see Fig. 31, top). As expected, the sliding friction force increases with the size of the microprobe, since the number of atoms that simultaneously attract it increases (see Fig. 31, bottom).

Figure 31. Dependence of the sliding friction force of the microprobe on the external force, N pressing it against the graphite surface. Top – probe curvature radius, 17 nm; bottom – probe curvature radius, 58 nm. It is seen that for small N the dependence is curvilinear, and at large it approaches a straight line, indicated by a dotted line. Data taken from Holscher and Schwartz (2002).

Thus, the sliding friction force of a microprobe depends on the area of ​​its contact with the surface, which contradicts the classical law of friction. It also turned out that the sliding friction force does not become zero in the absence of a force pressing the microprobe to the surface. Yes, this is understandable, since the surface atoms surrounding the microprobe are located so close to it that they attract it even in the absence of an external compression force. Therefore, the main assumption of the classical law - about the direct proportional dependence of the friction force on the compression force - is also not observed in nanotribology.

However, all these discrepancies between the classical law (1) and nanotribology data obtained using AFM can be easily eliminated. With an increase in the force pressing the sliding body, the number of microcontacts increases, which means that the total sliding friction force also increases. Therefore, there are no contradictions between the newly obtained data of scientists and the old law.

For a long time it was considered that by forcing one body to slide over another, we break small inhomogeneities of one body, which cling to the inhomogeneities of the surface of another, and in order to break these inhomogeneities, a friction force is needed. Therefore, old concepts often associate the occurrence of a friction force with damage to the microprotrusions of rubbing surfaces, their so-called wear. Nanotribological studies using AFM and other modern techniques have shown that the friction force between surfaces can be even in cases where they are not damaged. The reason for such a friction force is the constantly emerging and tearing bonds between rubbing atoms.

Why do nanoparticles melt at low temperatures?

When the particle size decreases, not only its mechanical properties change, but also its thermodynamic characteristics. For example, its melting point becomes much lower than that of normal-sized samples. Figure 35 shows how the melting temperature of aluminum nanoparticles changes as their size decreases. It can be seen that the melting point of a 4-nm particle is 140°C lower than that of a standard-sized aluminum sample.

Figure 35. Dependence of the melting temperature of aluminum nanoparticles T m on their radius R in angstroms (Å) 1 Å=0.1 nm.

Dependencies similar to the one shown in Fig. 35 have been obtained for many metals. For example, when the diameter of tin nanoparticles decreases to 8 nm, their melting point drops by 100°C (from 230°C to 130°C). In this case, the largest drop in the melting point (by more than 500°C) was found for gold nanoparticles.

Nanoparticles have almost all the atoms on the surface!

The reason for the decrease in the melting temperature of nanoparticles is that the atoms on the surface of all crystals are in special conditions, and the fraction of such “surface” atoms in nanoparticles becomes very large. Let us estimate this "surface" fraction for aluminum.

It is easy to calculate that 1 cm 3 of aluminum contains approximately 6. 10 22 atoms. For simplicity, we will assume that the atoms are located in the nodes of a cubic crystal lattice, then the distance between neighboring atoms in this lattice will be about 4 . 10 -8 cm. This means that the density of atoms on the surface will be 6 . 10 14 cm -2 .

Now let's take an aluminum cube with an edge of 1 cm. The number of surface atoms will be 36. 10 14 , and the number of atoms inside is 6 . 10 22 . Thus, the proportion of surface atoms in such an aluminum cube of "ordinary" size is only 6 . 10 -8 .

If we make the same calculations for a 5 nm aluminum cube, it turns out that 12% of all its atoms are already on the surface of such a “nanocube”. Well, on the surface of a 1 nm cube, in general, there are more than half of all atoms! The dependence of the “surface” fraction on the number of atoms is shown in Figure 36.

Figure 36. Dependence of the “surface” fraction of atoms (y-axis) on the cube root of their number N in a cube of a crystalline substance.

There is no order on the crystal surface

Since the beginning of the 60s of the last century, scientists have believed that atoms located on the surface of crystals are in special conditions. The forces that force them to be in the nodes of the crystal lattice act on them only from below. Therefore, surface atoms (or molecules) do not have to "evade the advice and embrace" of the molecules in the lattice, and if this happens, then several surface layers of atoms come to the same decision at once. As a result, a liquid film is formed on the surface of all crystals. By the way, ice crystals are no exception. Therefore, ice is slippery (see Fig. 37).

Figure 37. Schematic representation of a cross section of ice. The random arrangement of water molecules on the surface corresponds to a liquid film, and the hexagonal structure in the thickness corresponds to ice. Red circles are oxygen atoms; white - hydrogen atoms (from the book by K.Yu. Bogdanov "On the physics of eggs ... and not only", Moscow, 2008).

The thickness of the liquid film on the crystal surface increases with temperature, since the higher thermal energy of the molecules pulls out more surface layers from the crystal lattice. Theoretical estimates and experiments show that as soon as the thickness of the liquid film on the crystal surface begins to exceed 1/10 of the crystal size, the entire crystal lattice is destroyed and the particle becomes liquid. Therefore, the melting point of particles also gradually decreases with decreasing particle size (see Fig. 35).

Obviously, the “low melting point” of nanoparticles should be taken into account in any nanoproduction. It is known, for example, that the sizes of modern elements of electronic microcircuits are in the nanorange. Therefore, lowering the melting temperature of crystalline nanoobjects imposes certain restrictions on the temperature regimes of modern and future microcircuits.

Why can the color of nanoparticles depend on their size?

Many mechanical, thermodynamic and electrical characteristics of matter change in the nanoworld. Their optical properties are no exception. They also change in the nanoworld.

We are surrounded by objects of ordinary sizes, and we are accustomed to the fact that the color of an object depends only on the properties of the substance from which it is made or the dye with which it is painted. In the nanoworld, this view turns out to be unfair, and this distinguishes nanooptics from ordinary ones.

About 20-30 years ago, "nano-optics" did not exist at all. And how could there be nanooptics, if it follows from the course of conventional optics that light cannot "feel" nanoobjects, because their dimensions are much smaller than the wavelength of light λ = 400 – 800 nm. According to the wave theory of light, nano-objects should not have a shadow, and light cannot be reflected from them. It is also impossible to focus visible light on an area corresponding to a nanoobject. This means that it is impossible to see nanoparticles.

However, on the other hand, a light wave must still act on nano-objects, like any electromagnetic field. For example, light, falling on a semiconductor nanoparticle, can tear off one of the valence electrons from its atom by its electric field. This electron will become a conduction electron for some time, and then it will return “home” again, emitting a quantum of light corresponding to the width of the “forbidden zone” - the minimum energy necessary for the valence electron to become free (see Fig. 40).

Thus, semiconductors, even nanosized, must feel the light incident on them, while emitting light of a lower frequency. In other words, semiconductor nanoparticles in the light can become fluorescent, emitting light of a strictly defined frequency, corresponding to the width of the "gap".

Figure 40. Schematic representation of the energy levels and energy bands of an electron in a semiconductor. Under the action of blue light, an electron (white circle) breaks away from the atom, passing into the conduction band. After some time, it descends to the lowest energy level of this band and, emitting a quantum of red light, passes back into the valence band.

Glow according to size!

Although the fluorescent ability of semiconductor nanoparticles was known as early as the end of the 19th century, this phenomenon was described in detail only at the very end of the last century. And most interestingly, it turned out that the frequency of the light emitted by these particles decreased with the increase in the size of these particles (Fig. 41).

Figure 41. Fluorescence of suspensions of colloidal particles CdTe different sizes (from 2 to 5 nm, from left to right). All flasks are illuminated from above with blue light of the same wavelength. Adapted from H. Weller (Institute of Physical Chemistry, University of Hamburg).

As shown in fig. 41, the color of a suspension (suspension) of nanoparticles depends on their diameter. Fluorescence color dependence, i.e. its frequency, ν on the size of the nanoparticle means that the width of the “forbidden zone” Δ also depends on the size of the particle E. Looking at figures 40 and 41, it can be argued that with an increase in the size of nanoparticles, the width of the "gap", Δ E should decrease, because ΔE = h v. This dependence can be explained as follows.

It's easier to "break away" if there are a lot of neighbors around

The minimum energy required to detach a valence electron and transfer it to the conduction band depends not only on the charge of the atomic nucleus and the position of the electron in the atom. The more atoms around, the easier it is to tear off an electron, because the nuclei of neighboring atoms also attract it to themselves. The same conclusion is also valid for the ionization of atoms (see Fig. 42).

Figure 42. Dependence of the average number of nearest neighbors in the crystal lattice (ordinate) on the diameter of a platinum particle in angstroms (abscissa). 1 Å=0.1 nm. Taken from Frenkel et al. (J. Phys. Chem., B, v.105:12689, 2001).

On fig. 42. shows how the average number of nearest neighbors of a platinum atom changes with increasing particle diameter. When the number of atoms in a particle is small, a significant part of them are located on the surface, which means that the average number of nearest neighbors is much less than that which corresponds to the platinum crystal lattice (11). As the particle size increases, the average number of nearest neighbors approaches the limit corresponding to a given crystal lattice. From fig. 42 it follows that it is harder to ionize (tear off an electron) an atom if it is in a particle of small size, because on average, such an atom has few nearest neighbors.

Figure 43. Dependence of the ionization potential (work function, in eV) on the number of N atoms in an iron nanoparticle. Taken from a lecture by E. Roduner (Stuttgart, 2004).

On fig. 43 shows how the ionization potential (work function, in eV) changes for nanoparticles containing different numbers of iron atoms N. It can be seen that with growth N the work function drops, tending to a limiting value corresponding to the work function for samples of ordinary sizes. It turned out that the change BUT out with particle diameter D can be quite well described by the formula:

BUT out = BUT out0 + 2 Z e 2 / D , (6)

where BUT vyh0 - work function for samples of normal sizes, Z is the charge of the atomic nucleus, and e is the charge of an electron.

It is obvious that the width of the "forbidden zone" Δ E depends on the size of the semiconductor particle in the same way as the work function of metal particles (see formula 6) - decreases with increasing particle diameter. Therefore, the fluorescence wavelength of semiconductor nanoparticles increases with increasing particle diameter, which is illustrated in Figure 41.

Quantum dots are man-made atoms

Semiconductor nanoparticles are often referred to as "quantum dots". With their properties, they resemble atoms - "artificial atoms" having nanosizes. After all, electrons in atoms, moving from one orbit to another, also emit a quantum of light of a strictly defined frequency. But unlike real atoms, whose internal structure and radiation spectrum we cannot change, the parameters of quantum dots depend on their creators, nanotechnologists.

Quantum dots are already a handy tool for biologists trying to see the different structures inside living cells. The fact is that different cellular structures are equally transparent and not colored. Therefore, if you look at a cell through a microscope, you will not see anything but its edges. In order to make a certain structure of the cell visible, quantum dots were created that can stick to certain intracellular structures (Fig. 44).

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to color the cell in fig. 44 in different colors, three sizes of quantum dots were made. Molecules were glued to the smallest, glowing green light, capable of sticking to microtubules that make up the inner skeleton of the cell. Quantum dots of medium size could adhere to the membranes of the Golgi apparatus, while the largest ones, to the cell nucleus. When the cell was dipped in a solution containing all these quantum dots and kept in it for a while, they penetrated inside and stuck where they could. After that, the cell was rinsed in a solution that did not contain quantum dots and placed under a microscope. As expected, the aforementioned cellular structures became multicolored and clearly visible (Fig. 44).

Figure 44. Coloring different intracellular structures in different colors using quantum dots. Red is the core; green - microtubules; yellow - Golgi apparatus.

Nanotechnology in the fight against cancer

In 13% of cases, people die from cancer. This disease kills about 8 million people worldwide every year. Many types of cancer are still considered incurable. Scientific studies show that the use of nanotechnology can be a powerful tool in the fight against this disease.

Nanotechnology and medicine

Gold nanoparticles are heat bombs for cancer cells

A spherical silicon nanoparticle with a diameter of about 100 nm is coated with a gold layer 10 nm thick. Such a gold nanoparticle has the ability to absorb infrared radiation at a wavelength of 820 nm, while heating a thin layer of liquid around it by several tens of degrees.

Radiation with a wavelength of 820 nm is practically not absorbed by the tissues of our body. Therefore, if you make gold nanoparticles that stick only to cancer cells, then by passing radiation of this wavelength through the human body, you can heat and destroy these cells without damaging healthy cells of the body.

The scientists found that the membrane of normal cells differs from the membranes of cancer cells, and suggested applying molecules to the surface of gold nanoparticles to facilitate their adhesion to cancer cells. Such nanoparticles with the ability to adhere to cancer cells have been made for several types of cancer.

In experiments on mice, the effectiveness of gold nanoparticles in destroying cancer cells has been proven. First, cancerous diseases were induced in mice, then they were injected with the appropriate nanoparticles, and then subjected to radiation of a certain wavelength. It turned out that after a few minutes of such irradiation, most cancer cells died from overheating, while normal cells remained intact. Scientists have high hopes for this method of fighting cancer.

Dendrimers - capsules with poison for cancer cells

Cancer cells need a lot of folic acid to divide and grow. Therefore, folic acid molecules adhere very well to the surface of cancer cells, and if the outer shell of dendrimers contains folic acid molecules, then such dendrimers will selectively adhere only to cancer cells. With the help of such dendrimers, cancer cells can be made visible if some other molecules are attached to the shell of the dendrimers, which glow, for example, under ultraviolet light. By attaching a drug that kills cancer cells to the outer shell of the dendrimer, one can not only detect them, but also kill them (Fig. 45).

Figure 45. A dendrimer with folic acid molecules (purple) attached to its outer shell adheres only to cancer cells. Luminous fluorescein molecules (green) make it possible to detect these cells, methotrexate molecules (red) kill cancer cells. This makes it possible to selectively kill only cancer cells.

Silver nanoparticles are poison for bacteria

The physical properties of many substances depend on the size of the sample. Nanoparticles of a substance often have properties that are generally absent in samples of these substances that have ordinary sizes.

It is known that gold and silver do not participate in most chemical reactions. However, silver or gold nanoparticles not only become very good catalysts for chemical reactions (accelerate them), but also directly participate in chemical reactions. For example, conventional silver samples do not interact with hydrochloric acid, while silver nanoparticles react with hydrochloric acid, and this reaction proceeds according to the following scheme: 2Ag + 2HCl ® 2AgCl + H 2 .

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The high reactivity of silver nanoparticles explains the fact that they have a strong bactericidal effect - they kill some types of pathogenic bacteria. Silver ions make it impossible for many chemical reactions to occur inside bacteria, and therefore, in the presence of silver nanoparticles, many bacteria do not multiply. The so-called Gram-negative bacteria that cannot be stained by the Gram method (E. coli, Salmonella, etc.) are the most sensitive to the action of silver nanoparticles (Fig. 47).

Figure 47. The effect of various concentrations of silver nanoparticles 10-15 nm in size on the reproduction of Escherichia coli bacteria ( Escherichia coli) – (a) and salmonella ( Salmonella typhus) – (b). From left to right, both panels show photographs of Petri dishes with silver nanoparticle concentrations of 0, 5, 10, 25, and 35 µg/mL. Bacteria stain the nutrient solution of the plates yellowish (see the three leftmost plates). In the absence of bacteria, Petri dishes are colored dark brown due to the presence of silver nanoparticles. Taken from Shrivastava et al. (Nanotechnology, 18:225103, 2007).

To exploit the bactericidal property of silver nanoparticles, they have been incorporated into traditional materials such as bedding fabrics. Socks made from fabrics containing silver nanoparticles have been found to prevent foot fungal infections.

A layer of silver nanoparticles began to cover cutlery, doorknobs and even keyboards and mice for computers, which, as it was found, serve as breeding grounds for pathogenic bacteria. Silver nanoparticles began to be used in the creation of new coatings, disinfectants and detergents (including tooth and cleaning pastes, washing powders)

Bacteria and erythrocytes carriers of drug nanocapsules

A human disease, as a rule, is associated with a disease not of all, but often of a small part of its cells. But when we take pills, the medicine dissolves in the blood, and then with the bloodstream it acts on all cells - sick and healthy. At the same time, in healthy cells, unnecessary drugs can cause so-called side effects, such as allergic reactions. Therefore, a long-standing dream of doctors was the selective treatment of only diseased cells, in which the drug is delivered targeted and in very small portions. Nanocapsules with drugs that can only stick to certain cells could be the solution to this medical problem.

The main obstacle preventing the use of nanocapsules with drugs for targeted delivery to diseased cells is our immune system. As soon as the cells of the immune system encounter foreign bodies, including nanocapsules with drugs, they try to destroy and remove their remains from the bloodstream. And the more successfully they do it, the better our immunity. Therefore, if we introduce any nanocapsules into the bloodstream, our immune system will destroy the nanocapsules before they reach the target cells.

To deceive our immune system, it is proposed to use red blood cells (erythrocytes) to deliver nanocapsules. Our immune system easily recognizes “ours” and never attacks red blood cells. Therefore, if nanocapsules are attached to erythrocytes, then the cells of the immune system, having “seeing” “their own” erythrocyte floating through the blood vessel, will not “inspect” its surface, and the erythrocyte with attached nanocapsules will float further to the cells to whom these nanocapsules are addressed. Erythrocytes live on average for about 120 days. Experiments have shown that the duration of the "life" of nanocapsules attached to erythrocytes is 100 times longer than when they are simply injected into the blood.

An ordinary bacterium can also be loaded with nanoparticles with drugs, and then it can work as a transport for the delivery of these drugs to diseased cells. The size of nanoparticles is from 40 to 200 nanometers, their scientists have learned how to attach to the surface of bacteria using special molecules. Up to several hundreds of different types of nanoparticles can be placed on one bacterium (Fig. 59).

Figure 59. Method for delivering nanoparticles with drugs or DNA fragments (genes) for cell treatment.

Bacteria have a natural ability to invade living cells, making them ideal candidates for drug delivery. This is especially valuable in gene therapy, where it is necessary to deliver DNA fragments to their destination without killing a healthy cell. After the genes enter the cell nucleus, it begins to produce specific proteins, thus correcting the genetic disease. This opens up new possibilities in the field of gene therapy. It is also possible to force bacteria to carry nanoparticles with poison, for example, to kill cancer cells.

Nanofibers – scaffold for spinal cord repair

It is known that at present spinal cord injury is often untreatable. In these cases, a spinal cord injury chains a person to a wheelchair for life. The reason for such incurability of spinal cord injury is the protective function of our body - the rapid formation of a scar from tough connective tissue, which serves as the border between damaged and intact nerves that run along the spinal cord.

A scar always protects living cells from nearby dead ones and is formed when all tissues of the body are damaged. However, if the spinal cord is damaged, the resulting scar prevents the growth of nerves and the restoration of the main function of the spinal cord - to conduct nerve impulses from the brain to various parts of the body and back.

Nerves cannot grow through scars and empty cavities. To grow, they, like a house, need a frame or guides (scaffolding), as well as the absence of barriers. Thus, for the rapid recovery of spinal cord injury, it is necessary to (1) prevent the formation of a scar and (2) fill the space between damaged and undamaged nerve fibers with a scaffold. Nanotechnology solves both of the above tasks.

It is known that amphiphilic molecules, i.e. molecules in which hydrophilic and hydrophobic regions are spatially separated have the ability to self-assemble. These molecules eventually assemble into cylindrical nanofibers. At the same time, various molecules can be placed on the surface of these nanofibers, for example, they suppress the formation of scars and stimulate the growth of nervous tissue. Such nanofibers form lattice structures, creating a scaffold for nerve growth (Fig. 61). If the site of damage to the spinal cord is filled with such self-assembling fibers, then the damaged nerves will begin to grow through the site of damage, eliminating the consequences of the injury.

Figure 61. On the right is a schematic representation of a nanofiber formed from amphiphilic molecules that carry chemical structures that block scar growth and activate nerve growth (marked in different colors). On the left is a micrograph of a scaffold formed from nanofibers at the site of spinal cord injury; calibration, 200 nm. Taken from Hartgerink et al., Science, 294, 1684 (2001).

If, using a syringe (Fig. 62), a solution of such amphiphilic molecules is injected into the injury site within a day after the injury, they, having gathered into a three-dimensional network of nanofibers, will prevent the formation of a scar, and the nerve fibers will be able to grow, restoring the conduction of the impulse through the spinal cord and eliminating the effects of trauma. Such experiments were carried out on rats and were successful.

R Figure 62. Schematic representation of the damaged area of ​​the spinal cord (arrow) and a syringe with which a liquid with amphiphilic molecules is injected into this area. Adapted from Silva et al, Science, 303, 1352 (2004).

Nanotechnologies in everyday life and in industry

Nanotubes - tanks for storing hydrogen, the cleanest fuel

The reserves of coal, oil and gas on Earth are limited. In addition, burning conventional fuels leads to the accumulation of carbon dioxide and other harmful impurities in the atmosphere, and this in turn leads to global warming, the signs of which humanity is already experiencing. Therefore, today humanity faces a very important task - how to replace traditional fuels in the future?

It is most advantageous to use the most common chemical element in the universe, hydrogen, as a fuel. During the oxidation (combustion) of hydrogen, water is formed, and this reaction proceeds with the release of a very large amount of heat (120 kJ / kg). For comparison, the specific heat of combustion of gasoline and natural gas is three times less than that of hydrogen. It should also be taken into account that the combustion of hydrogen does not produce oxides of nitrogen, carbon and sulfur that are harmful to the environment.

Quite a few fairly cheap and environmentally friendly methods of hydrogen production have been proposed, however, the storage and transportation of hydrogen has so far been one of the unsolved problems of hydrogen energy. The reason for this is the very small size of the hydrogen molecule. Because of this, hydrogen can penetrate through the microscopic cracks and pores found in conventional materials, and its leakage into the atmosphere can lead to explosions. Therefore, the walls of oxygen storage cylinders should be thicker, which makes them heavier. For safety reasons, it is better to cool hydrogen cylinders to several tens of K, which makes the process of storing and transporting this fuel even more expensive.

The solution to the problem of storing and transporting hydrogen can be a device that plays the role of a “sponge”, which would have the ability to suck in hydrogen and hold it indefinitely. Obviously, such a hydrogen "sponge" should have a large surface area and chemical affinity for hydrogen. All these properties are present in carbon nanotubes.

As is known, in carbon nanotubes all atoms are on the surface. One of the mechanisms of hydrogen uptake by nanotubes is chemisorption, i.e., the adsorption of hydrogen H2 on the surface of a tube, followed by dissociation and the formation of C–H chemical bonds. Hydrogen bound in this way can be extracted from the nanotube, for example, by heating to 600°C. In addition, hydrogen molecules bind to the nanotube surface by physical adsorption via van der Waals interaction.

It is believed that the most efficient use of hydrogen as a fuel is its oxidation in a fuel cell (Fig. 46), in which chemical energy is directly converted into electrical energy. Thus, a fuel cell is similar to a galvanic cell, but differs from it in that the substances involved in the reaction are continuously fed into it from the outside.

Figure 46. Schematic representation of a fuel cell consisting of two electrodes separated by an electrolyte. Hydrogen is supplied to the anode, which, penetrating into the electrolyte through very small pores in the electrode material and participating in the chemisorption reaction, turns into positively charged ions. Oxygen is supplied to the cathode and water, the product of the reaction, is removed. Catalysts are used to speed up the reaction. The fuel cell electrodes are connected to a load (lamp).

According to the researchers, in order to create an efficient fuel cell, it is necessary to create a hydrogen "sponge", each cubic meter of which contained at least 63 kg of hydrogen. In other words, the mass of hydrogen stored in the "sponge" must be at least 6.5% of the mass of the "sponge". At present, with the help of nanotechnology, under experimental conditions, it has been possible to create hydrogen "sponges", the mass of hydrogen in which exceeds 18%, which opens up broad prospects for the development of hydrogen energy.

Nanophase materials are stronger

With a sufficiently large load, all materials break and at the point of fracture, adjacent layers of atoms forever move away from each other. However, the strength of many materials does not depend on how much force must be applied to separate two adjacent layers of atoms. In fact, it is much easier to break any material if it has cracks. Therefore, the strength of solid materials depends on how many and which microcracks there are in it, and how cracks propagate through this material. In those places where there is a crack, the force that tests the strength of the material is applied not to the entire layer, but to the chain of atoms located at the top of the crack, and therefore it is very easy to push the layers apart (see Fig. 48).

Figure 48. Schematic representation of a crack between two layers of atoms, expanding under the action of forces (red arrows).

The propagation of cracks is often hindered by the microstructure of the solid. If the body consists of microcrystals, such as metals, then a crack, splitting one of them in two, can stumble upon the outer surface of an adjacent microcrystal and stop. Thus, the smaller the size of the particles from which the material is molded, the more difficult it is for cracks to propagate along it.

Materials composed of nanoparticles are called nanophase materials. An example of a nanophase material would be nanophase copper, one of the fabrication methods for which is shown in Figure 49.

Figure 49. Fabrication of nanophase copper.

To make nanophase copper, a sheet of ordinary copper is heated to high temperature, at which copper atoms begin to evaporate from its surface. With a convective flow, these atoms move to the surface of a cold tube, on which they are deposited, forming conglomerates of nanoparticles. A dense layer of copper nanoparticles on the surface of a cold tube is nanophase copper.

Nanophase materials, which are often referred to as nanostructured, can be produced in a variety of ways, for example, by compressing nanoparticle powder at an elevated temperature (hot pressing).

Samples of materials "molded" from nanoparticles turn out to be much stronger than conventional ones. The mechanical load of a nanophase material, like that of a conventional one, causes the appearance of microcracks in it. However, the rectilinear propagation of this microcrack and its transformation into a macrocrack is hindered by numerous boundaries of nanoparticles that make up this material. Therefore, a microcrack hits the boundary of one of the nanoparticles and stops, while the sample remains intact.

Figure 50 shows how the strength of copper depends on the size of the microcrystals or nanoparticles of which it is composed. It can be seen that the strength of a sample of nanophase copper can be 10 times higher than the strength of ordinary copper, which usually consists of crystals about 50 μm in size.

Figure 50. Dependence of the strength of copper on the size of the granules (particles). Adapted from Scientific American, 1996, Dec, p. 74.

At small shear strains, the particles of nanophase materials are able to slightly shift relative to each other. Therefore, the fine-celled structure of nanophase materials is stronger not only under tensile deformations, but also under bending, when adjacent layers of the sample change their length in different ways.

TiO 2 nanoparticles - nanosoap and UV trap

Titanium dioxide, TiO 2 is the most common titanium compound on earth. Titanium dioxide powder has a dazzling white color and is therefore used as a coloring agent in the manufacture of paints, paper, toothpastes and plastics. The reason for this whiteness of titanium dioxide powder is its very high refractive index (n=2.7).

Titanium oxide TiO 2 has a very strong catalytic activity - it accelerates the course of chemical reactions. In the presence of ultraviolet radiation, titanium dioxide splits water molecules into free radicals - hydroxyl groups OH - and superoxide anions O 2 - (Fig. 51).

Figure 51. Schematic representation of the formation of free radicals OH - and O 2 - during the catalysis of water on the surface of titanium dioxide in the presence of sunlight.

The activity of the resulting free radicals is so high that on the surface of titanium dioxide, any organic compounds decompose into carbon dioxide and water. It should be noted that this only occurs in sunlight, which is known to contain an ultraviolet component.

The catalytic activity of titanium dioxide increases with a decrease in the size of its particles, since the ratio of the particle surface to their volume increases in this case. Therefore, titanium nanoparticles become very effective, and they are used to purify water, air and various surfaces from organic compounds which are generally harmful to humans.

Photocatalysts based on titanium dioxide nanoparticles can be included in the composition of road concrete. Experiments show that during the operation of such roads, the concentration of nitrogen monoxide is much lower than over conventional roads. Thus, the inclusion of titanium dioxide nanoparticles in the composition of concrete can improve the ecology around highways. In addition, it is proposed to add powder from these nanoparticles to automotive fuel, which should also reduce the content of harmful impurities in exhaust gases.

A film of titanium dioxide nanoparticles deposited on glass is transparent and invisible to the eye. However, such glass, under the action of sunlight, is able to self-clean from organic contaminants, turning any organic dirt into carbon dioxide and water. Glass treated with titanium oxide nanoparticles is devoid of greasy stains and therefore is well wetted by water. As a result, such glass fogs less, as water droplets immediately spread along the glass surface, forming a thin transparent film.

Unfortunately, titanium dioxide stops working indoors because In artificial light, there is practically no ultraviolet radiation. However, scientists believe that by slightly changing the structure of titanium dioxide, it will be possible to make it sensitive to the visible part of the solar spectrum. Based on such titanium dioxide nanoparticles, it will be possible to make a coating, for example, for toilet rooms, as a result of which the content of bacteria and other organic matter on the surfaces of toilets can be reduced by several times.

Due to its ability to absorb ultraviolet radiation, titanium dioxide is already used in the manufacture of sunscreens, such as creams. Cream manufacturers have begun to use titanium dioxide in the form of nanoparticles, which are so small that they provide almost absolute transparency of sunscreen.

Self-cleaning nanograss and the "lotus effect"

Nanotechnology makes it possible to create a surface similar to a massage microbrush. Such a surface is called nanograss, and it is a set of parallel nanowires (nanorods) of the same length, located at an equal distance from each other (Fig. 52).

Figure 52. An electron micrograph of a nanograss consisting of silicon rods 350 nm in diameter and 7 µm high, spaced 1 µm apart.

A drop of water, falling on a nanograss, cannot penetrate between the nanograss, as this is prevented by the high surface tension of the liquid. After all, in order to penetrate between nanoblades, a drop needs to increase its surface, and this requires additional energy costs. Therefore, the drop “floats on pointe shoes”, between which there are air bubbles. As a result, the sticking (adhesion) forces between the droplet and the nanograss become very small. This means that it becomes unfavorable for the drop to spread and wet the “prickly” nanograss, and it rolls up into a ball, demonstrating a very high contact angle q, which is a quantitative measure of wettability (Fig. 53).

Figure 53. A drop of water on a nanograss.

To make the wettability of a nanograss even smaller, its surface is covered with a thin layer of a hydrophobic polymer. And then not only water, but also any particles will never stick to the nanograss, because. touch it only at a few points. Therefore, the particles of dirt that are on the surface covered with nanovilli either fall off it themselves or are carried away by rolling drops of water.

Self-cleaning of a fleecy surface from dirt particles is called the "lotus effect", because. lotus flowers and leaves are pure even when the water around is muddy and dirty. This happens due to the fact that the leaves and flowers are not wetted with water, so drops of water roll off them like balls of mercury, leaving no trace and washing away all the dirt. Even drops of glue and honey fail to stay on the surface of lotus leaves.

It turned out that the entire surface of the lotus leaves is densely covered with micropimples about 10 microns high, and the pimples themselves, in turn, are covered with even smaller microvilli (Fig. 54). Studies have shown that all these micro-pimples and villi are made of wax, which is known to have hydrophobic properties, making the surface of lotus leaves look like nanograss. It is the pimply structure of the surface of lotus leaves that significantly reduces their wettability. For comparison, Figure 54 shows the relatively smooth surface of a magnolia leaf, which is not self-cleaning.

Figure 54. Photomicrograph of the surface of lotus and magnolia leaves. One micropimple is shown schematically at the bottom left. Taken from planta (1997), 202: 1-8.

Thus, nanotechnologies make it possible to create self-cleaning coatings and materials that also have water-repellent properties. Materials made from such fabrics remain always clean. Self-cleaning windshields are already being produced, the outer surface of which is covered with nanovilli. On such glass, the "wipers" have nothing to do. There are constantly clean rims for car wheels on sale, self-cleaning using the “lotus effect”, and now you can paint the outside of the house with paint that dirt does not stick to.

Nanobatteries are powerful and durable

Unlike transistors, battery miniaturization is very slow. The size of galvanic batteries, reduced to a unit of power, has decreased over the past 50 years by only 15 times, and the size of the transistor has decreased over the same time by more than 1000 times and is now about 100 nm. It is known that the size of an autonomous electronic circuit is often determined not by its electronic filling, but by the size of the current source. At the same time, the smarter the electronics of the device, the larger the battery it requires. Therefore, for further miniaturization of electronic devices, it is necessary to develop new types of batteries. Here again, nanotechnology helps.

Nanoparticles increase the surface of electrodes

The larger the area of ​​the electrodes of batteries and accumulators, the more current they can give. To increase the area of ​​electrodes, their surface is coated with conductive nanoparticles, nanotubes, etc.

Toshiba in 2005 created a prototype of a lithium-ion rechargeable battery, the negative electrode of which was coated with lithium titanate nanocrystals, as a result of which the electrode area increased several tens of times. The new battery is capable of reaching 80% of its capacity in just one minute of charging, while conventional lithium-ion batteries charge at a rate of 2-3% per minute and take an hour to fully charge.

In addition to a high recharge rate, batteries containing nanoparticle electrodes have an extended service life: after 1000 charge / discharge cycles, only 1% of its capacity is lost, and the total life of new batteries is more than 5 thousand cycles. And yet, these batteries can operate at temperatures down to -40 o C, while losing only 20% of the charge versus 100% for typical modern batteries already at -25 o C.

Since 2007, batteries with conductive nanoparticle electrodes have been on the market, which can be installed on electric vehicles. These lithium-ion batteries are capable of storing energy up to 35 kW. hour, charging to maximum capacity in just 10 minutes. Now the driving range of an electric car with such batteries is 200 km, but the next model of these batteries has already been developed, which allows increasing the mileage of an electric car to 400 km, which is almost comparable to the maximum mileage of gasoline cars (from refueling to refueling).

Nano switch for battery

One of the main drawbacks of modern batteries is that they completely lose their power in a few years, even if they do not work, but lie in a warehouse (15% of energy is lost every year). The reason for the drop in energy over time in batteries is that even for non-working batteries, the electrodes and electrolyte always come into contact with each other, and therefore the ionic composition of the electrolyte and the surface of the electrodes gradually change, which causes a drop in battery power.

H To avoid electrolyte contact with the electrodes during battery storage, their surface can be protected with water-resistant nanofilaments (see Figure 55), simulating the "lotus effect" described above.

Figure 55. Schematic representation of a "nanograss" of nanorods 300 nm in diameter, growing on one of the electrodes of the battery. Due to the hydrophobic properties of the nanowire material, the bluish electrolyte solution cannot approach the surface of the "red" electrode, and the battery does not lose its power for many years. Adapted from Scientific American, 2006, Feb, p. 73.

It is known that adhesion (sticking) can be controlled using an external electric field. Everyone has seen how small pieces of paper, crumbs, dust, etc. stick to an electrified plastic comb. Wettability is determined by adhesion, and therefore an electric field applied between a liquid and a solid surface always increases the wettability of the latter.

The hydrophobic coating of the nanowires protects the surface of one of the battery electrodes from contact with the electrolyte (Fig. 55). However, if we want to use a battery, then it is enough to apply a small voltage to the nanowires, and they become hydrophilic, as a result of which the electrolyte fills the entire space between the electrodes, making the battery workable.

It is believed that the nanotechnology of switching on and off described above will be in demand for batteries in various sensors, for example, those dropped from an aircraft in hard-to-reach areas, which are planned to be used only after a few years or in some special cases on a signal.

Nanotube Capacitors

Researchers believe that the electric capacitor, invented about 300 years ago, could be an excellent battery if improved with the help of nanotechnology. Unlike galvanic current sources, a capacitor can serve as an accumulator of electrical energy indefinitely. At the same time, you can charge the capacitor much faster than any battery.

The only drawback of an electric capacitor, in comparison with galvanic current sources, is its low specific energy intensity (the ratio of stored energy to volume). At present, the specific energy capacity of capacitors is approximately 25 times less than that of batteries and accumulators.

It is known that the capacitance and energy capacity of a capacitor are directly proportional to the surface area of ​​its plates. With the help of nanotechnologies, to increase the area of ​​the capacitor plates, it is possible to grow a forest of conducting nanotubes on their surface (Fig. 56). As a result, the energy capacity of such a capacitor can increase thousands of times. It is believed that such capacitors will become common current sources in the very near future.

Figure 56. The surface of one of the capacitor plates, which is a forest of vertically oriented carbon nanotubes.

For those who want to connect the future with nanotechnology

Now many Russian universities are training specialists in the direction of "nanotechnology". Nanotechnologies faculties and departments appear in many prestigious universities. Everyone understands the prospects of this direction, understand its progressiveness ... and even, perhaps, its benefits. Recent years have been marked by a rapid growth of interest in nanotechnologies and the growth of investments in them all over the world. And this is quite understandable, given that nanotechnologies provide a high potential for economic growth, on which the quality of life of the population, technological and defense security, resource and energy conservation depend. Now almost all developed countries have national programs in the field of nanotechnology. They are of a long-term nature, and their financing is carried out at the expense of funds allocated both from state sources and from other funds.

List of universities where you can study in the specialty "nanotechnology"

1. Moscow State University M.V. Lomonosov,

2. GOU VPO "Moscow Institute of Physics and Technology (State University)",

3. GOU VPO "Moscow State Technical University named after N.E. Bauman,

4. GOU VPO "Moscow State Institute of Steel and Alloys (Technological University)",

5. GOU VPO "Moscow State Institute of Electronic Technology (Technical University)",

6. FGU VPO "St. Petersburg State University",

7. GOU VPO "Taganrog State Radio Engineering University" (as part of the Southern Federal University),

8. N.I. Lobachevsky Nizhny Novgorod State University,

9. FGU VPO "Tomsk State University".

10. GOU VPO "Far Eastern State University",

11. Samara State Aerospace University named after Academician S.P. Korolev,

12. GOU VPO "Saint Petersburg State Mining Institute named after G.V. Plekhanov (Technical University)",

13. GOU VPO "Tomsk State University of Control Systems and Radioelectronics",

14. GOU VPO "Tomsk Polytechnic University",

15. GOU VPO "Novosibirsk State University",

16. National Research Nuclear University "MEPhI",

17. GOU VPO "St. Petersburg State Polytechnic University",

18. GOU VPO "Moscow Power Engineering Institute (Technical University)",

19. Saint Petersburg State Electrotechnical University "LETI" named after V.I. Ulyanov (Lenin)",

20. GOU VPO "St. Petersburg State University of Information Technologies, Mechanics and Optics",

21. SEI VPO "Belgorod State University",

22. State Educational Institution of Higher Professional Education "Peoples' Friendship University of Russia",

23. GOU VPO "Ural State University named after A.M. Gorky",

24. Saratov State University named after N.G. Chernyshevsky,

25. SEI VPO "Vladimir State University",

26. GOU VPO "Moscow State University of Civil Engineering",

27. GOU VPO "Far Eastern State Technical University (FEPI named after V.V. Kuibyshev)",

28. GOU VPO "Novosibirsk State Technical University",

29. SEI VPO "South Ural State University",

30. GOU VPO "Perm State Technical University",

31. Kazan State Technical University named after A.N. Tupolev,

32. GOU VPO "Ufa State Aviation Technical University",

33. GOU VPO "Tyumen State University",

34. GOU VPO "Ural State Technical University - UPI named after the first President of Russia B.N. Yeltsin",

35. GOU VPO "Yakutsk State University named after M.K. Amosov",

36. GOU VPO "Vyatka State University",

37. FGOU VPO "Russian State University named after Immanuel Kant",

38. GOU VPO "Moscow Pedagogical State University",

39. GOU VPO "Russian State University of Oil and Gas named after I.M. Gubkin",

40. Tambov State University named after G.R. Derzhavin.

Bibliography

http://abitur.nica.ru/

http://www.med.umich.edu/opm/newspage/2005/nanoparticles.htm.

http://probes.invitrogen.com/servlets/photo?fileid=g002765&company=probes

http://en.wikipedia.org/wiki/Optical_tweezers.

http://www.nanometer.ru/2007/06/06/atomno_silovaa_mikroskopia_2609.html#

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ESSAY

on this topic: Henabouttechnology in modern world

Performed: 7 B class student

Karimova Sabina

Supervisor: Shamshur G.A

Physics teacher

Karaganda 2014

Introduction

1 . Nanotechnology in the modern world

1.1 History of nanotechnology

1.2 What is nanotechnology

2. Application of nanotechnology

2.1 Nanotechnology in space

2.2 Nanotechnology in medicine

2.3 Nanotechnology in agriculture and industry

2.4 Nanotechnologies in electronics, art

3. Dangers associated with nanotechnology

3.1 Biohazard

Conclusion

INTRODUCTION

At present, few people know what nanotechnology is, although the future lies behind this science. The main goal of my work is to get acquainted with nanotechnology. I also want to find out the application of this science in various industries and find out if nanotechnology can be dangerous to humans. nanotechnology nanobot biological space electronics

The field of science and technology called nanotechnology is relatively recent. The prospects for this science are grandiose. The very particle "nano" means one billionth of a value. For example, a nanometer is one billionth of a meter. These dimensions are similar to those of molecules and atoms. The precise definition of nanotechnologies is as follows: nanotechnologies are technologies that manipulate matter at the level of atoms and molecules (which is why nanotechnologies are also called molecular technology). The impetus for the development of nanotechnology was a lecture by Richard Feynman, in which he scientifically proves that from the point of view of physics there are no obstacles to creating things directly from atoms. To designate a means of efficient manipulation of atoms, the concept of an assembler was introduced - a molecular nanomachine that can build any molecular structure. An example of a natural assembler is a ribosome that synthesizes protein in living organisms. Obviously, nanotechnology is not just a separate part of knowledge, it is a large-scale, comprehensive area of ​​research related to the fundamental sciences. We can say that almost any subject that is studied at school will in one way or another be connected with the technologies of the future. The most obvious is the connection of "nano" with physics, chemistry and biology. Apparently, it is these sciences that will receive the greatest impetus for development in connection with the approaching nanotechnical revolution.

1. NANOTECHNOLOGIES IN THE MODERN WORLD

1.1 Historythe emergence of nanotechnology

The grandfather of nanotechnology can be considered the Greek philosopher Democritus. He first used the word "atom" to describe the smallest particle of matter. For more than twenty centuries, people have tried to penetrate the secret of the structure of this particle. The solution of this unbearable task for many generations of physicists became possible in the first half of the 20th century after the creation of an electron microscope by German physicists Max Knoll and Ernst Ruska, which for the first time made it possible to study nanoobjects.

Many sources, primarily English-speaking, the first mention of methods that will later be called nanotechnology, is associated with Richard Feynman's famous speech “There's Plenty of Roo at the Bottom”, made by him in 1959 At the annual meeting of the American Physical Society at the California Institute of Technology, Richard Feynman suggested that it would be possible to mechanically move single atoms, with a manipulator of the appropriate size, at least such a process would not contradict the physical laws known today.

He suggested doing this manipulator in the following way. It is necessary to build a mechanism that would create its own copy, only an order of magnitude smaller. The created smaller mechanism must again create its copy, again an order of magnitude smaller, and so on until the dimensions of the mechanism are commensurate with the dimensions of the order of one atom. At the same time, it will be necessary to make changes in the structure of this mechanism, since the forces of gravity acting in the macrocosm will have less and less influence, and the forces of intermolecular interactions will increasingly affect the operation of the mechanism. The last stage - the resulting mechanism will assemble its copy from individual atoms. In principle, the number of such copies is unlimited, it will be possible to create an arbitrary number of such machines in a short time. These machines will be able to assemble macrothings in the same way, by atom-by-atom assembly. This will make things an order of magnitude cheaper - such robots (nanorobots) will need to be given only the required number of molecules and energy, and write a program to assemble the necessary items. Until now, no one has been able to refute this possibility, but no one has yet managed to create such mechanisms. The fundamental disadvantage of such a robot is the impossibility of creating a mechanism from a single atom.

Here is how R. Feynman described the manipulator he proposed:

I think about creating an electrically controlled system , which uses "servicing robots" made in the usual way in the form of copies of the operator's "hands" reduced by four times. Such micromechanisms will be able to easily perform operations on a reduced scale. I'm talking about tiny robots equipped with servo motors and small "arms" that can turn equally small bolts and nuts, drill very small holes, etc. In short, they will be able to do all the work in 1:4 scale. To do this, of course, you must first make the necessary mechanisms, tools and manipulator arms in one-fourth of the usual size (in fact, it is clear that this means reducing all contact surfaces by 16 times). At the last stage, these devices will be equipped with servomotors (with a power reduction of 16 times) and connected to a conventional electrical control system. After that, it will be possible to use manipulator arms reduced by 16 times! The scope of such microrobots, as well as micromachines, can be quite wide - from surgical operations to transportation and processing of radioactive materials. I hope that the principle of the proposed program, as well as the unexpected problems and brilliant opportunities associated with it, are clear. Moreover, one can think about the possibility of a further significant reduction in scale, which, of course, will require further structural changes and modifications (by the way, at a certain stage, it may be necessary to abandon the “hands” of the usual shape), but will make it possible to manufacture new, much more advanced devices. described type. Nothing prevents you from continuing this process and creating as many tiny machines as you like, since there are no restrictions associated with the placement of machines or their material consumption. Their volume will always be much less than the volume of the prototype. It is easy to calculate that the total volume of 1 million machine tools reduced by a factor of 4000 (and, consequently, the mass of materials used for the manufacture) will be less than 2% of the volume and mass of a conventional machine tool of normal size. It is clear that this immediately removes the problem of the cost of materials. In principle, millions of identical miniature factories could be organized, on which tiny machines would continuously drill holes, stamp parts, etc. As we shrink in size, we will constantly encounter very unusual physical phenomena. Everything you encounter in life depends on large-scale factors. In addition, there is also the problem of "sticking" of materials under the action of intermolecular forces (the so-called van der Waals forces), which can lead to effects that are unusual for macroscopic scales. For example, a nut will not separate from a bolt when loosened, and in some cases will "stick" tightly to the surface, etc. There are several physical problems of this type to keep in mind when designing and building microscopic mechanisms.

1.2 What is nanotechnology

Having appeared quite recently, nanotechnologies are increasingly entering the field of scientific research, and from it into our daily life. The developments of scientists are increasingly dealing with objects of the microcosm, atoms, molecules, molecular chains. Artificially created nano-objects constantly surprise researchers with their properties and promise the most unexpected prospects for their application.

The basic unit of measurement in nanotechnological research is the nanometer - a billionth of a meter. Molecules and viruses are measured in such units, and now elements of new generation computer chips. It is on the nanoscale that all the basic physical processes that determine macrointeractions take place.

Nature itself prompts a person to the idea of ​​creating nano-objects. Any bacterium, in fact, is an organism consisting of nanomachines: DNA and RNA copy and transmit information, ribosomes form proteins from amino acids, mitochondria produce energy. Obviously, at this stage in the development of science, it occurs to scientists to copy and improve these phenomena.

The creation of a scanning tunneling microscope in 1980 allowed scientists not only to distinguish between individual atoms, but also to move them and assemble structures from them, in particular, components of future nanomachines - engines, manipulators, power supplies, controls. Nanocapsules are being created for the direct delivery of drugs in the body, nanotubes are 60 times stronger than steel, flexible solar cells and many other amazing devices.

One of the main types of nanoobjects are nanoparticles. When a substance is divided into particles tens of nanometers in size, the total total surface of particles in a substance increases hundreds of times, and as a result, the interaction of material atoms with the environment increases, because now they are almost all on the surface. This phenomenon is used in modern technology. For example, silver nanopowder is used in medicine, which has antiseptic properties. Titanium dioxide nanoparticles repel dirt and create self-cleaning surfaces. Aluminum nanopowder accelerates the combustion of solid propellant. New lithium-ion batteries containing nanoparticles are charged in just a couple of minutes. There are already many such examples. Fullerenes were another element discovered in the 1980s. These structures resemble balls made of carbon atoms.

Another well-known nanoelement is the carbon nanotube. This is a monatomic layer of carbon, rolled into a cylinder with a diameter of several nanometers. These objects were first obtained in 1952, but only in 1991 did they attract the attention of scientists. The strength of these tubes exceeds the strength of steel dozens of times, they can withstand heating up to 2500 degrees and pressure of thousands of atmospheres. This strength is also inherent in the materials made on their basis. In electronics, nanotubes can be used as good conductors, as well as semiconductors.

Another nanomaterial is graphene - a two-dimensional carbon layer, a plane consisting of carbon atoms. This material was first obtained by Russian physicists working in England. Many scientists believe that this material, which has unique properties, will become the basis of microprocessors in the future, displacing modern semiconductors. In addition, this material is also incredibly durable.

All these nanoelements are increasingly being used in various fields of technology - from medicine to space research.

One of the most promising areas of application of nanotechnologies is, of course, medicine. Scientists have been working on the problem of delivering drugs directly to cells affected by infection or disease for many years. The main design of the transport is as follows: a capsule made of biomaterial 50-200 nanometers in size, in which drug molecules are located. Outside, the capsule is covered with polymer chains, which determine when the capsule reaches the target tissues, after which the drug will be injected and the shell will disintegrate. The last stages can be postponed and their onset can be controlled remotely, for example, by heating or ultrasound.

All these and many other ideas are now not only at the development stage, but also at the stage of practical application. The results of some tests stagger the imagination, some end in failure. At the same time, the enthusiasm of scientists is growing about the approaching era of the embodiment of the most fantastic ideas, for example, complete control over all natural processes or nanofactories that collect any objects directly from atoms. Many scenarios for the development of the future of nanotechnologies have been created, including those that do not bode well for mankind. However, it can be said that the interest in nanotechnologies is now so great that it sometimes determines the direction they take.

2. APPLICATIONS OF NANOTECHNOLOGIES

The penetration of nanotechnology into the spheres of human activity can be represented as a tree of nanotechnology. The application has the form of a tree, the branches of which represent the main applications, and the branches from the large branches represent the differentiation within the main applications at a given point in time.

Today (2000 - 2010) there is the following picture:

Biological sciences involve the development of gene tagging technology, implant surfaces, antimicrobial surfaces, targeted drugs, tissue engineering, oncological therapy;

Simple fibers suggest the development of paper technology, cheap building materials, lightweight boards, auto parts, heavy-duty materials;

Nanoclips involve the production of new fabrics, glass coating, "smart" sands, paper, carbon fibers;

Corrosion protection by means of nano-additives to copper, aluminum, magnesium, steel;

The catalysts are intended for use in agriculture, deodorization, and food production.

Easily cleanable materials are used in everyday life, architecture, the dairy and food industries, the transport industry, and sanitation. This is the production of self-cleaning glasses, hospital equipment and tools, anti-mold coating, easy-cleaning ceramics.

Biocoatings are used in sports equipment and bearings.

Optics as a sphere of application of nanotechnology includes such areas as electrochromics, the production of optical lenses. These are new photochromic optics, easy-to-clean optics and coated optics.

Ceramics in the field of nanotechnology makes it possible to obtain electroluminescence and photoluminescence, printing pastes, pigments, nanopowders, microparticles, membranes.

Computer technology and electronics as a sphere of application of nanotechnology will develop electronics, nanosensors, household (embedded) microcomputers, visualization tools and energy converters. Further it is the development of global networks, wireless communications, quantum and DNA computers.

Nanomedicine, as a sphere of application of nanotechnology, is nanomaterials for prosthetics, "smart" prostheses, nanocapsules, diagnostic nanoprobes, implants, DNA reconstructors and analyzers, "smart" and precision instruments, directional pharmaceuticals.

Space as a sphere of application of nanotechnology will open the prospect for mechanoelectric converters solar energy, nanomaterials for space applications.

Ecology as a sphere of application of nanotechnology is the restoration of the ozone layer, weather control.

2.1 Nanotechnology in space

A revolution is raging in space. Satellites and nanoprojects began to be created weights up to 20 kilograms.

A system of microsatellites has been created, it is less vulnerable to attempts to destroy it. It is one thing to shoot down a colossus in orbit weighing several hundred kilograms, or even tons, immediately putting out of action all space communications or intelligence, and another when there is a whole swarm of microsatellites in orbit. The failure of one of them in this case will not disrupt the operation of the system as a whole. Accordingly, the reliability requirements for each satellite can be reduced.

Young scientists believe that among other things, the creation of new technologies in the field of optics, communication systems, methods of transmitting, receiving and processing large amounts of information should be attributed to the key problems of microminiaturization of satellites. We are talking about nanotechnologies and nanomaterials, which make it possible to reduce the mass and dimensions of devices launched into space by two orders of magnitude. For example, the strength of nanonickel is 6 times higher than that of ordinary nickel, which makes it possible, when used in rocket engines, to reduce the mass of the nozzle by 20-30%. Reducing the mass of space technology solves many problems: it prolongs the spacecraft's stay in space, allows it to fly farther and carry more of any useful equipment for research. At the same time, the problem of energy supply is being solved. Miniature devices will soon be used to study many phenomena, for example, the impact of solar rays on processes on Earth and in near-Earth space.

Today, space is not exotic, and exploration of it is not only a matter of prestige. First of all, this is a matter of national security and national competitiveness of our state. It is the development of supercomplex nanosystems that can become a national advantage of the country. Like nanotechnology, nanomaterials will give us the opportunity to talk seriously about manned flights to various planets. solar system. It is the use of nanomaterials and nanomechanisms that can make manned flights to Mars and exploration of the Moon's surface a reality. Another extremely popular direction in the development of microsatellites is the creation of remote sensing of the Earth (ERS). A market for consumers of information began to form with a resolution of satellite images of 1 m in the radar range and less than 1 m in the optical range (first of all, such data are used in cartography).

It is expected that in 2025 the first assemblers based on nanotechnology will appear. It is theoretically possible that they will be able to construct any object from ready-made atoms. It will be enough to design any product on a computer, and it will be assembled and multiplied by the assembly complex of nanorobots. But these are still the simplest possibilities of nanotechnology. It is known from theory that rocket engines would work optimally if they could change their shape depending on the mode. Only with the use of nanotechnology will this become a reality. A structure stronger than steel, lighter than wood, will be able to expand, contract and bend, changing the force and direction of the thrust. Spaceship can change in about an hour. Nanotechnology, built into the space suit and ensuring the circulation of substances, will allow a person to stay in it for an unlimited time. Nanorobots are also able to realize the dream of science fiction about the colonization of other planets, these devices will be able to create on them the habitat necessary for human life. It will become possible to automatically build orbital systems, any structures in the oceans, on the surface of the earth and in the air (experts predict this by 2025).

2.2 Nanotechnology in medicine

Recent advances in nanotechnology, according to scientists, can be very useful in the fight against cancer. An anti-cancer drug has been developed directly to the target - into cells affected by a malignant tumor. A new system based on a material known as biosilicon. Nanosilicone has a porous structure (ten atoms in diameter), which is convenient to introduce drugs, proteins and radionuclides. Having reached the goal, the biosilicon begins to disintegrate, and the medicines delivered by it are taken to work. Moreover, according to the developers, new system allows you to adjust the dosage of the drug.

For recent years Employees of the Center for Biological Nanotechnology are working on the creation of microsensors that will be used to detect cancer cells in the body and fight this terrible disease.

A new technique for recognizing cancer cells is based on the implantation of tiny spherical reservoirs made of synthetic polymers called dendrimers (from the Greek dendron - tree) into the human body. These polymers have been synthesized in the last decade and have a fundamentally new, non-solid structure that resembles the structure of coral or wood. Such polymers are called hyperbranched or cascaded. Those in which branching is regular are called dendrimers. In diameter, each such sphere, or nanosensor, reaches only 5 nanometers - 5 billionths of a meter, which makes it possible to place billions of such nanosensors in a small area of ​​\u200b\u200bspace.

Once inside the body, these tiny sensors will penetrate the lymphocytes, the white blood cells that provide the body's defense response against infection and other pathogens. When the immune response of lymphoid cells to a certain disease or environmental condition - a cold or exposure to radiation, for example - the protein structure of the cell changes. Each nanosensor, coated with special chemicals, will begin to glow with such changes.

To see this glow, scientists are going to create a special device that scans the retina. The laser of such a device should detect the glow of lymphocytes when they pass one by one through the narrow capillaries of the fundus. If there are enough labeled sensors in the lymphocytes, a 15-second scan would be needed to detect damage to the cell, the scientists say.

Here, the greatest impact of nanotechnology is expected, since it affects the very basis of the existence of society - man. Nanotechnology reaches such a dimensional level of the physical world, at which the distinction between living and non-living becomes unsteady - these are molecular machines. Even a virus can partly be considered a living system, since it contains information about its construction. But the ribosome, although it consists of the same atoms as the whole organic matter, does not contain such information and therefore is only an organic molecular machine. Nanotechnology in its developed form involves the construction of nanorobots, molecular machines of inorganic atomic composition, these machines will be able to build their copies, having information about such a construction. Therefore, the line between living and non-living begins to blur. To date, only one primitive walking DNA robot has been created.

Nanomedicine is represented by the following possibilities:

1. Labs on a chip, targeted drug delivery in the body.

2. DNA - chips (creation of individual drugs).

3. Artificial enzymes and antibodies.

4. Artificial organs, artificial functional polymers (substitutes for organic tissues). This direction is closely connected with the idea of ​​artificial life and in the future leads to the creation of robots with artificial consciousness and capable of self-healing at the molecular level. This is due to the expansion of the concept of life beyond the organic

5. Nanorobots-surgeons (biomechanisms that carry out changes and required medical actions, recognition and destruction of cancer cells). This is the most radical application of nanotechnology in medicine will be the creation of molecular nanorobots that can destroy infections and cancerous tumors, repair damaged DNA, tissues and organs, duplicate entire life support systems of the body, change the properties of the body.

Considering a single atom as a brick or "detail", nanotechnologies are looking for practical ways to construct materials with desired characteristics from these details. Many companies already know how to assemble atoms and molecules into certain structures.

In the future, any molecules will be assembled like a children's designer. For this, it is planned to use nanorobots (nanobots). Any chemically stable structure that can be described can, in fact, be constructed. Since a nanobot can be programmed to build any structure, in particular to build another nanobot, they will be very cheap. Working in huge groups, nanobots will be able to create any objects with low cost and high accuracy. In medicine, the problem of using nanotechnologies lies in the need to change the structure of the cell at the molecular level, i.e. to carry out "molecular surgery" with the help of nanobots. The creation of molecular robotic doctors is expected, which can "live" inside the human body, eliminating all damage that occurs, or preventing the occurrence of such. By manipulating individual atoms and molecules, nanobots will be able to repair cells. The predicted time for the creation of robotic doctors is the first half of the 21st century.

Despite the current state of affairs, nanotechnologies, as a cardinal solution to the problem of aging, are more than promising.

This is due to the fact that nanotechnologies have great potential for commercial applications in many industries, and, accordingly, in addition to serious government funding, research in this direction is being carried out by many large corporations.

It is quite possible that after being improved to ensure "eternal youth", nanobots will no longer be needed or they will be produced by the cell itself.

To achieve these goals, humanity needs to solve three main questions:

1. Design and build molecular robots that can repair molecules.

2. Design and create nanocomputers that will control nanomachines.

3. Create Full description of all molecules in the human body, in other words, to create a map of the human body at the atomic level.

The main difficulty with nanotechnology is the problem of creating the first nanobot. There are several promising directions.

One of them is to improve the scanning tunneling microscope or atomic force microscope and achieve positional accuracy and gripping power.

Another path to the creation of the first nanobot leads through chemical synthesis. Perhaps designing and synthesizing ingenious chemical components that would be capable of self-assembly in solution.

And another way leads through biochemistry. Ribosomes (inside the cell) are specialized nanobots, and we can use them to build more versatile robots.

These nanobots will be able to slow down the aging process, treat individual cells and interact with individual neurons.

Research works have begun relatively recently, but the pace of discoveries in this area is extremely high, many believe this is the future of medicine.

2.3 Nanotechnologies in agriculture and industry

Nanotechnology has the potential to revolutionize agriculture. Molecular robots will be able to produce food by “freeing” plants and animals from this. To this end, they will use any "grass material": water and air, where there are the main necessary elements - carbon, oxygen, nitrogen, hydrogen, aluminum and silicon, and the rest, as for "ordinary" living organisms, will be required in microquantities. For example, it is theoretically possible to produce milk directly from grass, bypassing the intermediate link - a cow. A person does not have to kill animals to eat a fried chicken or a piece of smoked lard. Consumables will be produced "directly at home"

Nanofood (nanofood) - the term is new, obscure and unsightly. Food for nanohumans? Very small portions? Food made in nanofactories? Of course not. But still, it is an interesting direction in the food industry. It turns out that nanoeating is a whole set of scientific ideas that are already on the way to implementation and application in industry. First, nanotechnology can provide food manufacturers with unique opportunities for total real-time monitoring of the quality and safety of products directly in the production process. We are talking about diagnostic machines using various nanosensors or so-called quantum dots that can quickly and reliably detect the smallest chemical contaminants or dangerous biological agents in products. And food production, and its transportation, and storage methods can receive their share of useful innovations from the nanotechnology industry. According to scientists, the first mass-produced machines of this kind will appear in mass food production in the next four years. But more radical ideas are also on the agenda. Are you ready to swallow nanoparticles you can't see? But what if nanoparticles are purposefully used to deliver beneficial substances and drugs to precisely selected parts of the body? What if such nanocapsules can be introduced into food products? So far, no one has used nanofood, but preliminary developments are already underway. Experts say that edible nanoparticles can be made from silicon, ceramics or polymers. And, of course, organic matter. And if everything is clear with regard to the safety of the so-called "soft" particles, similar in structure and composition to biological materials, then "hard" particles composed of inorganic substances- this is a big blank spot at the intersection of two territories - nanotechnology and biology. Scientists still cannot say which routes such particles will travel in the body, and where they will stop as a result. This remains to be seen. But some experts are already drawing futuristic pictures of the benefits of nano-eaters. In addition to delivering valuable nutrients to the right cells. The idea is as follows: everyone buys the same drink, but then the consumer will be able to control the nanoparticles himself so that the taste, color, aroma and concentration of the drink will change before his eyes.

2.4 Nanotechnologies in electronics, art

With the advent of new means of nanomanipulation, it is possible to create mechanical computers capable of functionally repeating a modern microprocessor in a cube with an edge of 100 nm. It is planned to create nanorobots with a size of only 1-2 microns, equipped with onboard mechanocomputers and energy sources, which will be completely autonomous and will be able to perform various functions, up to self-copying.

Music, literature, ballet, theater and everything related to the expression of human creativity have always stood somewhat apart from scientific and technological progress. Thus, the prospects for the development of science and technology also determine the path of art. In 2001, Japanese scientists, using advanced laser technology, created the world's smallest sculpture. It depicts an angry bull, turning around to attack. The dimensions of the “microbull” are impressive: 10 microns in length and 7 microns in height - no more than those of red blood cells in human blood. You can only see it with a super-powerful microscope. .

3. HAZARDS ASSOCIATED WITH NANOTECHNOLOGIES

With all the advantages of nanotechnology, they can also pose a threat to human health. While enthusiastically anticipating the positive changes that the industrial revolution will bring, we should not be so naive as to not think about the possible dangers and problems. Many prominent scientists of our time are not in vain trying to draw attention not only to the positive prospects for the future, but also to possible negative consequences. Some scientists, such as Bill Joy, are calling for research in nanotechnology and other fields to be stopped before it harms humanity. Fears of nanotechnologies began to appear in 1986, after the publication of Drexler's "Machines of Creation", where he not only painted a utopian picture of the nanotechnological future, but also touched on the "reverse", impartial side of this medal.

3.1. biological threat

For example, it is known that tiny particles of carbon can enter the human brain through the respiratory tract and have a devastating effect on the body. We are talking about C 60 - one of the three main forms of pure carbon. To determine the toxicity of the molecules, American biologist Eva Oberdörster first tested C 60 on water blocks by adding these molecules to 10-liter tanks with these small crustaceans. After 48 hours, the biologist looked at the daphnia and saw increasing mortality in the aquarium. The revealed effect makes the nanomaterial a "moderate poison": it is slightly more toxic than nickel, but still not as dangerous as chemicals found in cigarette smoke and car exhaust. Oberdörster conducted the next experiment with the participation of perches. C 60 loaded into an aquarium with fish. After the same two days, none of the fish died or showed changes in behavior, but the perch showed serious damage to the membranes of brain cells. The damage was 17 times higher compared to fish swimming in ordinary water. Of course, not all nanomaterials have the same properties that are harmful to living beings.

CONCLUSION

Formed historically, to the present moment, nanoteXnology, having conquered the theoretical field of social consciousness, continues to penetrate into its everyday layer. A number of exceptionally important results have already been obtained in nanotechnology, allowing us to hope for significant progress in the development of many other areas of science and technology (medicine and biology, chemistry, ecology, energy, mechanics, etc.).

Space as a sphere of application of nanotechnology will open up prospects for mechanoelectric solar energy converters, nanomaterials for space applications. It is the development of supercomplex nanosystems that can become a national advantage of the country. Like nanotechnology, nanomaterials will give us the opportunity to talk seriously about manned flights to various planets in the solar system. It is the use of nanomaterials and nanomechanisms that can make manned flights to Mars and exploration of the Moon's surface a reality.

Nanomedicine, as a sphere of application of nanotechnology, is nanomaterials for prosthetics, "smart" prostheses, nanocapsules, diagnostic nanoprobes, implants, DNA reconstructors and analyzers, "smart" and precision instruments, directional pharmaceuticals. In medicine, the problem of using nanotechnologies lies in the need to change the structure of the cell at the molecular level, i.e. to carry out "molecular surgery" with the help of nanobots. It is expected the creation of molecular robotic doctors that can "live" inside the human body, eliminating all damage that occurs, or preventing the occurrence of such. By manipulating individual atoms and molecules, nanobots will be able to repair cells. The predicted time for the creation of robotic doctors is the first half of the 21st century.

Nanotechnology is also used in the food industry. And food production, and its transportation, and storage methods can receive their share of useful innovations from the nanotechnology industry. In addition to delivering valuable nutrients to the right cells, the following is assumed: everyone buys the same drink, but then the consumer will be able to control the nanoparticles so that the taste, color, aroma and concentration of the drink will change before his eyes.

Having clarified the concept of nanotechnology, outlining its prospects and dwelling on possible dangers and threats, I would like to draw a conclusion. I believe that nanotechnology is a young science, the results of the development of which can change the world around us beyond recognition. And what these changes will be - useful, incomparably facilitating life, or harmful, threatening humanity - depends on the mutual understanding and rationality of people. And mutual understanding and reasonableness directly depend on the level of humanity, which implies the responsibility of a person for his actions. Therefore, the most important need in the last years before the inevitable nanotechnological "boom" is the education of philanthropy. Only reasonable and humane people can turn nanotechnologies into a stepping stone to understanding the Universe and their place in this Universe.

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Russian President Dmitry Medvedev is confident that the country has all the conditions for the successful development of nanotechnology.

Nanotechnology is a new area of ​​science and technology that has been actively developing in recent decades. Nanotechnologies include the creation and use of materials, devices and technical systems, the functioning of which is determined by the nanostructure, that is, its ordered fragments ranging in size from 1 to 100 nanometers.

The prefix "nano", which came from the Greek language ("nanos" in Greek - dwarf), means one billionth part. One nanometer (nm) is one billionth of a meter.

The term "nanotechnology" (nanotechnology) was coined in 1974 by professor-materials scientist from the University of Tokyo Norio Taniguchi (Norio Taniguchi), who defined it as "manufacturing technology that allows to achieve ultra-high precision and ultra-small dimensions ... of the order of 1 nm ..." .

Nanoscience is clearly distinguished from nanotechnology in the world literature. The term nanoscale science is also used for nanoscience.

In Russian and in the practice of Russian legislation and normative documents the term "nanotechnologies" includes "nanoscience", "nanotechnologies", and sometimes even "nanoindustry" (areas of business and production where nanotechnologies are used).

The most important component of nanotechnology are nanomaterials, that is, materials whose unusual functional properties are determined by the ordered structure of their nanofragments ranging in size from 1 to 100 nm.

- nanoporous structures;
- nanoparticles;
- nanotubes and nanofibers
- nanodispersions (colloids);
- nanostructured surfaces and films;
- nanocrystals and nanoclusters.

Nanosystem technology- completely or partially created on the basis of nanomaterials and nanotechnologies, functionally complete systems and devices, the characteristics of which are fundamentally different from those of systems and devices of a similar purpose, created using traditional technologies.

Applications of nanotechnology

It is almost impossible to list all the areas in which this global technology can significantly affect technological progress. We can name just a few of them:

- elements of nanoelectronics and nanophotonics (semiconductor transistors and lasers;
- photodetectors; Solar cells; various sensors)
- devices for ultra-dense recording of information;
- telecommunications, information and computing technologies; supercomputers;
- video equipment - flat screens, monitors, video projectors;
- molecular electronic devices, including switches and electronic circuits at the molecular level;
- nanolithography and nanoimprinting;
- fuel cells and energy storage devices;
- devices of micro- and nanomechanics, including molecular motors and nanomotors, nanorobots;
- nanochemistry and catalysis, including combustion control, coating, electrochemistry and pharmaceuticals;
- aviation, space and defense applications;
- devices for monitoring the state of the environment;
- targeted delivery of drugs and proteins, biopolymers and healing of biological tissues, clinical and medical diagnostics, creation of artificial muscles, bones, implantation of living organs;
- biomechanics; genomics; bioinformatics; bioinstrumentation;
- registration and identification of carcinogenic tissues, pathogens and biologically harmful agents;
- safety in agriculture and food production.

Computers and microelectronics

Nanocomputer- a computing device based on electronic (mechanical, biochemical, quantum) technologies with the size of logical elements of the order of several nanometers. The computer itself, developed on the basis of nanotechnology, also has microscopic dimensions.

DNA computer- a computing system that uses the computational capabilities of DNA molecules. Biomolecular computing is a collective name for various techniques related to DNA or RNA in one way or another. In DNA computing, data is not represented in the form of zeros and ones, but in the form of a molecular structure built on the basis of the DNA helix. The role of software for reading, copying and managing data is performed by special enzymes.

Atomic force microscope- high-resolution scanning probe microscope, based on the interaction of the cantilever needle (probe) with the surface of the sample under study. Unlike a scanning tunneling microscope (STM), it can examine both conductive and non-conductive surfaces even through a liquid layer, which makes it possible to work with organic molecules (DNA). The spatial resolution of an atomic force microscope depends on the size of the cantilever and the curvature of its tip. The resolution reaches atomic horizontally and significantly exceeds it vertically.

Antenna oscillator- On February 9, 2005, an oscillator antenna with a size of about 1 micron was received in the laboratory of Boston University. This device has 5,000 million atoms and is capable of oscillating at a frequency of 1.49 gigahertz, which allows you to transfer huge amounts of information with it.

Nanomedicine and pharmaceutical industry

A direction in modern medicine based on the use of the unique properties of nanomaterials and nanoobjects for tracking, designing and changing human biological systems at the nanomolecular level.

DNA nanotechnologies- use the specific bases of DNA molecules and nucleic acids to create clearly defined structures on their basis.

Industrial synthesis of molecules of drugs and pharmacological preparations of a well-defined shape (bis-peptides).

At the beginning of 2000, thanks to the rapid progress in the technology of manufacturing nano-sized particles, an impetus was given to the development of a new field of nanotechnology - nanoplasmonics. It turned out to be possible to transmit electromagnetic radiation along a chain of metal nanoparticles by excitation of plasmon oscillations.

Robotics

Nanobots- robots created from nanomaterials and comparable in size to a molecule, with the functions of movement, processing and transmission of information, execution of programs. Nanorobots capable of creating copies of themselves, i.e. self-reproducing are called replicators.

At present, electromechanical nanodevices with limited mobility have already been created, which can be considered prototypes of nanorobots.

Molecular rotors- Synthetic nanoscale motors capable of generating torque when enough energy is applied to them.

Place of Russia among the countries developing and producing nanotechnologies

The world leaders in terms of total investment in the field of nanotechnology are the EU countries, Japan and the United States. Recently, Russia, China, Brazil and India have significantly increased investments in this industry. In Russia, the amount of financing within the framework of the program "Development of nanoindustry infrastructure in the Russian Federation for 2008-2010" will amount to 27.7 billion rubles.

The latest (2008) report of the London-based research firm Cientifica, called the "Nanotechnology Outlook Report," says the following verbatim about Russian investment: "Although the EU still ranks first in terms of investment, China and Russia have already overtaken the United States."

There are such areas in nanotechnology where Russian scientists became the first in the world, having obtained results that laid the foundation for the development of new scientific trends.

Among them are the production of ultrafine nanomaterials, the design of single-electron devices, as well as work in the field of atomic force and scanning probe microscopy. Only at a special exhibition held within the framework of the XII St. Petersburg Economic Forum (2008), 80 specific developments were presented at once.

Russia already produces a number of nanoproducts that are in demand on the market: nanomembranes, nanopowders, nanotubes. However, according to experts, Russia is ten years behind the United States and other developed countries in the commercialization of nanotechnological developments.

The material was prepared on the basis of information from open sources

Nanotechnology is a field of fundamental and applied science and technology that deals with a combination of theoretical justification, practical methods of research, analysis and synthesis, as well as methods for the production and use of products with a given atomic structure by controlled manipulation of individual atoms and molecules.

Story

Many sources, primarily in English, associate the first mention of methods that would later be called nanotechnology with Richard Feynman's famous speech “There's Plenty of Room at the Bottom”, made by him in 1959 at the California Institute of Technology at the annual meeting of the American Physical Society. Richard Feynman suggested that it was possible to mechanically move single atoms with a manipulator of the appropriate size, at least such a process would not contradict the physical laws known today.

He suggested doing this manipulator in the following way. It is necessary to build a mechanism that would create its own copy, only an order of magnitude smaller. The created smaller mechanism must again create its copy, again an order of magnitude smaller, and so on until the dimensions of the mechanism are commensurate with the dimensions of the order of one atom. At the same time, it will be necessary to make changes in the structure of this mechanism, since the forces of gravity acting in the macrocosm will have less and less influence, and the forces of intermolecular interactions and van der Waals forces will increasingly affect the operation of the mechanism.

The last stage - the resulting mechanism will assemble its copy from individual atoms. In principle, the number of such copies is unlimited, it will be possible to create an arbitrary number of such machines in a short time. These machines will be able to assemble macrothings in the same way, atom-by-atom assembly. This will make things an order of magnitude cheaper - such robots (nanorobots) will need to be given only the required number of molecules and energy, and write a program to assemble the necessary items. Until now, no one has been able to refute this possibility, but no one has yet managed to create such mechanisms. In the course of a theoretical study of this possibility, hypothetical doomsday scenarios have emerged that suggest that nanorobots will absorb the entire biomass of the Earth, carrying out their self-reproduction program (the so-called "gray goo" or "gray goo").

The first assumptions about the possibility of studying objects at the atomic level can be found in the book "Opticks" by Isaac Newton, published in 1704. In the book, Newton expresses the hope that the microscopes of the future will someday be able to explore "the mysteries of corpuscles."

The term "nanotechnology" was first used by Norio Taniguchi in 1974. He called this term the production of products with a size of several nanometers. In the 1980s, the term was used by Eric K. Drexler in his books Engines of Creation: The Coming Era of Nanotechnology and Nanosystems: Molecular Machinery, Manufacturing, and Computation.

What can nanotechnology do?

Here are just a few of the areas where nanotechnology promises breakthroughs:

The medicine

Nanosensors will ensure progress in the early diagnosis of diseases. This will increase the chances of recovery. We can beat cancer and other diseases. Old cancer drugs destroyed not only diseased cells, but also healthy ones. With the help of nanotechnology, the drug will be delivered directly to the diseased cell.

DNA nanotechnologies- use the specific bases of DNA molecules and nucleic acids to create clearly defined structures on their basis. Industrial synthesis of molecules of drugs and pharmacological preparations of a well-defined shape (bis-peptides).

In early 2000, thanks to the rapid progress in the technology of manufacturing nano-sized particles, an impetus was given to the development of a new field of nanotechnology - nanoplasmonics. It turned out to be possible to transmit electromagnetic radiation along a chain of metal nanoparticles by excitation of plasmon oscillations.

Construction

Nanosensors of building structures will monitor their strength, detect any threats to integrity. Objects built using nanotechnology can last up to five times longer than modern structures. Homes will adapt to the needs of residents, keeping them cool in summer and warm in winter.

Energy

We will be less dependent on oil and gas. Modern solar panels have an efficiency of about 20%. With the use of nanotechnology, it can grow by 2-3 times. Thin nanofilms on the roof and walls can provide energy to the whole house (if, of course, there is enough sun).

mechanical engineering

All bulky equipment will be replaced by robots - easily controlled devices. They will be able to create any mechanisms at the level of atoms and molecules. For the production of machines, new nanomaterials will be used that can reduce friction, protect parts from damage, and save energy. These are far from all the areas in which nanotechnologies can (and will!) be applied. Scientists believe that the emergence of nanotechnology is the beginning of a new scientific and technological revolution that will greatly change the world in the 21st century. However, it is worth noting that nanotechnologies do not enter the real practice very quickly. Not many devices (mostly electronics) work "with nano". This is partly due to the high cost of nanotechnology and the not very high return on nanotechnology products.

Probably, in the near future, with the help of nanotechnologies, high-tech, mobile, easily controlled devices will be created that will successfully replace the automated, but difficult to manage and bulky equipment of today. So, for example, over time, computer-controlled biorobots will be able to perform the functions of the current bulky pumping stations.

• DNA computer- a computing system that uses the computational capabilities of DNA molecules. Biomolecular computing is a collective name for various techniques related to DNA or RNA in one way or another. In DNA computing, data is not represented in the form of zeros and ones, but in the form of a molecular structure built on the basis of the DNA helix. The role of software for reading, copying and managing data is performed by special enzymes.
• Atomic force microscope– high-resolution scanning probe microscope, based on the interaction of the cantilever needle (probe) with the surface of the sample under study. Unlike a scanning tunneling microscope (STM), it can examine both conductive and non-conductive surfaces even through a liquid layer, which makes it possible to work with organic molecules (DNA). The spatial resolution of an atomic force microscope depends on the size of the cantilever and the curvature of its tip. The resolution reaches atomic horizontally and significantly exceeds it vertically.
• Antenna oscillator- On February 9, 2005, an oscillator antenna with a size of about 1 micron was obtained in the laboratory of Boston University. This device has 5,000 million atoms and is capable of oscillating at a frequency of 1.49 gigahertz, which allows you to transfer huge amounts of information with it.

10 Nanotechnologies With Amazing Potential

Try to remember some canonical invention. Probably, someone now imagined a wheel, someone an airplane, and someone an iPod. And how many of you have thought about the invention of a completely new generation - nanotechnology? This world is little known, but it has incredible potential that can give us really fantastic things. The amazing thing is that the direction of nanotechnology did not exist until 1975, even though scientists began working in this area much earlier.

The human naked eye is able to recognize objects up to 0.1 mm in size. Today we will talk about ten inventions that are 100,000 times smaller.

Electrically conductive liquid metal

With electricity, a simple liquid metal alloy of gallium, iridium, and tin can be made to form complex shapes or wind circles inside a Petri dish. It can be said with some degree of probability that this is the material from which the famous T-1000 series cyborg was created, which we could see in Terminator 2.

“A soft alloy behaves like a smart form, capable of self-deforming if necessary, taking into account the changing surrounding space through which it moves. Just like a cyborg from a popular sci-fi movie could do, ”says Jin Li from Tsinghua University, one of the researchers involved in this project.

This metal is biomimetic, that is, it mimics biochemical reactions, although it is not itself a biological substance.

This metal can be controlled by electrical discharges. However, he himself is able to move independently, due to the emerging load imbalance, which is created by the difference in pressure between the front and back of each drop of this metal alloy. And although scientists believe that this process may be the key to converting chemical energy into mechanical energy, molecular material is not going to be used to build evil cyborgs in the near future. The whole process of "magic" can only take place in a sodium hydroxide solution or saline solution.

Nanoplasters

Researchers at the University of York are working to create special patches that will be designed to deliver all the necessary drugs into the body without any use of needles and syringes. Plasters of quite normal size are glued to the hand, delivering a certain dose of drug nanoparticles (small enough to penetrate through the hair follicles) inside your body. Nanoparticles (each less than 20 nanometers in size) will find harmful cells on their own, kill them and be removed from the body along with other cells as a result of natural processes.

Scientists note that in the future, such nanoplasters can be used in the fight against one of the most terrible diseases on Earth - cancer. Unlike chemotherapy, which in such cases is most often an integral part of the treatment, nanopatch will be able to individually find and destroy cancer cells while leaving healthy cells intact. The nanopatch project was named NanJect. It is being developed by Atif Syed and Zakaria Hussain, who in 2013, while still students, received the necessary sponsorship as part of a crowdsourcing fundraising campaign.

Nanofilter for water

When this film is used in combination with a thin stainless steel mesh, the oil is repelled and the water in the area becomes pristine.

Interestingly, nature itself inspired scientists to create a nanofilm. Lotus leaves, also known as water lilies, have the opposite of nanofilms: instead of oil, they repel water. This is not the first time scientists have peeped at these amazing plants for their no less amazing properties. The result of this, for example, was the creation of superhydrophobic materials in 2003. As for the nanofilm, researchers are trying to create a material that mimics the surface of water lilies and enrich it with molecules of a special cleanser. The coating itself is invisible to the human eye. Production will be inexpensive: approximately $1 per square foot.

Submarine Air Purifier

It is unlikely that anyone thought about what kind of air the crews of submarines have to breathe, except for the crew members themselves. Meanwhile, the purification of air from carbon dioxide must be carried out immediately, since in one voyage through the light crews of the submarine the same air has to pass hundreds of times. To clean the air from carbon dioxide, amines are used, which have a very unpleasant odor. To address this issue, a cleaning technology was created, called SAMMS (an acronym for Self-Assembled Monolayers on Mesoporous Supports). It proposes the use of special nanoparticles placed inside ceramic granules. The substance has a porous structure, due to which it absorbs excess carbon dioxide. The different types of SAMMS cleanings interact with different molecules in air, water, and earth, but all of these cleaning options are incredibly effective. Just one tablespoon of these porous ceramic granules is enough to clean an area equal to one football field.

Nanoconductors

Researchers at Northwestern University (USA) figured out how to create an electrical conductor at the nanoscale. This conductor is a solid and strong nanoparticle that can be tuned to carry electric current in various opposite directions. The study shows that each such nanoparticle is able to emulate the operation of "a rectifier, switches and diodes." Each 5 nanometer-thick particle is coated with a positively charged chemical and surrounded by negatively charged atoms. Applying an electrical discharge reconfigures the negatively charged atoms around the nanoparticles.

The potential of the technology, according to scientists, is unprecedented. Based on it, you can create materials that "are capable of independently changing for certain computer computing tasks." The use of this nanomaterial will actually "reprogram" the electronics of the future. Hardware upgrades will be as easy as software upgrades.

Nanotech Charger

When this thing is created, you will no longer need to use any wired chargers. The new nanotechnology works like a sponge, only it absorbs non-liquid. It sucks kinetic energy from the environment and sends it directly to your smartphone. The basis of the technology is the use of a piezoelectric material that generates electricity while in a state of mechanical stress. The material is endowed with nanoscopic pores that turn it into a flexible sponge.

The official name of this device is "nanogenerator". Such nanogenerators could one day become part of every smartphone on the planet, or part of the dashboard of every car, and perhaps even part of every pocket of clothing - gadgets will be charged right in it. In addition, the technology has the potential to be used at a larger scale, for example, in industrial equipment. At least that's what researchers at the University of Wisconsin-Madison think, who created this amazing nanosponge.

artificial retina

The Israeli company Nano Retina is developing an interface that will directly connect to the neurons of the eye and transmit the result of neural simulation to the brain, replacing the retina and returning people to sight.

An experiment on a blind chicken showed hope for the success of the project. The nanofilm allowed the chicken to see the light. True, the final stage of the development of an artificial retina to restore vision to people is still far away, but the progress in this direction cannot but rejoice. Nano Retina is not the only company involved in such developments, but it is their technology that is currently seen as the most promising, efficient and adaptive. The last point is the most important since we are talking about a product that will integrate into someone's eyes. Similar developments have shown that solid materials are unsuitable for such applications.

Since the technology is developed at the nanotechnological level, it eliminates the use of metal and wires, as well as avoiding the low resolution of the simulated image.

Glowing clothes

Shanghai scientists have developed reflective threads that can be used in the production of clothing. The basis of each thread is a very thin stainless steel wire, which is coated with special nanoparticles, a layer of electroluminescent polymer, and a protective sheath of transparent nanotubes. The result is very light and flexible threads that can glow under the influence of their own electrochemical energy. At the same time, they operate at much lower power than conventional LEDs.

The disadvantage of the technology lies in the fact that the “light reserve” of the threads is still enough for only a few hours. However, the developers of the material optimistically believe that they will be able to increase the "resource" of their product at least a thousand times. Even if they succeed, the solution to another drawback is still in question. Most likely, it will be impossible to wash clothes based on such nanothreads.

Nanoneedles for the restoration of internal organs

The nanoplasters we talked about above are designed specifically to replace needles. What if the needles themselves were only a few nanometers in size? In this case, they could change our understanding of surgery, or at least significantly improve it.

More recently, scientists have conducted successful laboratory tests on mice. With the help of tiny needles, researchers were able to inject nucleic acids into rodent organisms that promote the regeneration of organs and nerve cells and thereby restore lost performance. When the needles perform their function, they remain in the body and after a few days completely decompose in it. At the same time, scientists did not find any side effects during operations to restore the blood vessels of the muscles of the back of rodents using these special nanoneedles.

If we take into account human cases, then such nanoneedles can be used to deliver the necessary funds to the human body, for example, in organ transplantation. Special substances will prepare the surrounding tissues around the transplanted organ for rapid recovery and eliminate the possibility of rejection.

3D chemical printing

University of Illinois chemist Martin Burke is a real Willy Wonka from the world of chemistry. Using a collection of "building material" molecules for various purposes, he can create a huge number of different chemicals, endowed with all sorts of "amazing and yet natural properties." For example, one such substance is ratanin, which can only be found in a very rare Peruvian flower.

The potential for synthesizing substances is so huge that it will make it possible to produce molecules used in medicine in the creation of LED diodes, solar cell cells and those chemical elements that even the best chemists on the planet took years to synthesize.

The capabilities of the current prototype of a three-dimensional chemical printer are still limited. He is able to create only new drugs. However, Burke hopes that one day he will be able to create a consumer version of his amazing device, which will have much more capabilities. It is quite possible that in the future such printers will act as a kind of home pharmacists.

Does nanotechnology pose a threat to human health or the environment?

There is not so much information about the negative impact of nanoparticles. In 2003, one study showed that carbon nanotubes could damage the lungs in mice and rats. A 2004 study showed that fullerenes can accumulate and cause brain damage in fish. But both studies used large doses of the substance under unusual conditions. According to one of the experts, chemist Kristen Kulinowski (USA), "it would be advisable to limit the impact of these nanoparticles, despite the fact that currently there is no information about their threat to human health."

Some commentators also argue that the widespread use of nanotechnology may lead to social and ethical risks. So, for example, if the use of nanotechnology initiates a new industrial revolution, it will lead to job losses. Moreover, nanotechnologies can change the idea of ​​a person, since their use will help prolong life and significantly increase the body's resistance. “No one can deny that the widespread use of mobile phones and the Internet has brought about enormous changes in society,” says Kristen Kulinowski. “Who dares to say that nanotechnology will not have a greater impact on society in the coming years?”

Place of Russia among the countries developing and producing nanotechnologies

The world leaders in terms of total investment in the field of nanotechnology are the EU countries, Japan and the United States. Recently, Russia, China, Brazil and India have significantly increased investments in this industry. In Russia, the amount of financing within the framework of the program "Development of the Nanoindustry Infrastructure in the Russian Federation for 2008-2010" will amount to 27.7 billion rubles.

In the latest (2008) report of the London-based research firm Cientifica, called the Nanotechnology Outlook Report, the following is written about Russian investments: “Although the EU still ranks first in terms of investment, China and Russia have already overtaken the United States.”

There are such areas in nanotechnology where Russian scientists became the first in the world, having obtained results that laid the foundation for the development of new scientific trends.

Among them are the production of ultrafine nanomaterials, the design of single-electron devices, as well as work in the field of atomic force and scanning probe microscopy. Only at a special exhibition held within the framework of the XII St. Petersburg Economic Forum (2008), 80 specific developments were presented at once. Russia already produces a number of nanoproducts that are in demand on the market: nanomembranes, nanopowders, nanotubes. However, according to experts, Russia is ten years behind the United States and other developed countries in the commercialization of nanotechnological developments.

Nanotechnology in art

A number of works by the American artist Natasha Vita-Mor deal with nanotechnological topics.

In contemporary art, a new direction "nanoart" (nanoart) has emerged - a type of art associated with the creation by the artist of sculptures (compositions) of micro- and nano-sizes (10 −6 and 10 −9 m, respectively) under the influence of chemical or physical processes of processing materials , photographing the obtained nano-images using an electron microscope and processing black-and-white photographs in a graphics editor.

In the well-known work of the Russian writer N. Leskov “Lefty” (1881), there is a curious fragment: “If,” he says, “there was a better small scope, which magnifies five million, so you would deign,” he says, “to see that on each horseshoe, the master's name is displayed: which Russian master made that horseshoe. An increase of 5,000,000 times is provided by modern electron and atomic force microscopes, which are considered the main tools of nanotechnology. Thus, the literary hero Lefty can be considered the first "nanotechnologist" in history.

Feynman's 1959 lecture "There's a lot of room down there" on the ideas of how to create and use nanomanipulators coincide almost textually with the science fiction story "Microhands" by the famous Soviet writer Boris Zhitkov, published in 1931. Some of the negative consequences of the uncontrolled development of nanotechnologies are described in the works of M. Crichton ("Swarm"), S. Lem ("Inspection on the spot" and "Peace on Earth"), S. Lukyanenko ("Nothing to share").

The protagonist of the novel “Transman” by Y. Nikitin is the head of a nanotechnology corporation and the first person to experience the action of medical nanorobots.

In the sci-fi series Stargate SG-1 and Stargate Atlantis, one of the most technologically advanced races are two races of "replicators" that arose as a result of unsuccessful experiments with the use and description of various applications of nanotechnology. In the film The Day the Earth Stood Still, starring Keanu Reeves, an alien civilization passes a death sentence on humanity and almost destroys everything on the planet with the help of self-replicating nano-replicant beetles, devouring everything in its path.