Brief introduction of nanotechnology
Nano-science and technology is based on many modern advanced science and technology. It is a combination of modern science, chaotic physics, quantum mechanics, mesoscopic physics, molecular biology and modern technology, computer technology, microelectronics, scanning tunneling microscope technology and nuclear analysis technology. Nano-science and technology will trigger a series of new science and technology, such as nano-physics, nano-biology and nano-chemistry.
Theoretical significance of nanotechnology
Nanotechnology * * * Nanotechnology * *, also known as nanotechnology, is a technology to study the properties and applications of materials with structural dimensions between 1 nm and 100 nm. After the invention of 198 1 year scanning tunneling microscope, a molecular world with the length of 1 to 100 nm was born, and its ultimate goal is to directly construct products with specific functions from atoms or molecules. So nanotechnology is actually a technology that uses single atoms and molecules to arrange substances.
From the current research, there are three concepts about nanotechnology:
The first is the molecular nanotechnology put forward by American scientist Dr. drexler in the book "Creating Machines from 65438 to 0986". According to this concept, we can make the machine of combining molecules practical, so that we can combine various molecules at will and make any molecular structure. The nanotechnology of this concept has not made significant progress.
The second concept defines nanotechnology as the limit of micromachining technology. That is, the technology of artificially forming nano-scale structures through nano-precision "processing". This nano-scale processing technology also makes the miniaturization of semiconductors reach the limit. Even if the existing technology continues to develop, it will eventually reach the limit in theory, because if the line width of the circuit is gradually reduced, the insulation film forming the circuit will become extremely thin, destroying the insulation effect. In addition, there are problems such as fever and trembling. In order to solve these problems, research? A href ='' target =' _ blank'> Cough closed? How can Angel be good at judging the international market? /p & gt；
The third concept is put forward from a biological point of view. It turns out that organisms have nano-scale structures in cells and biomembranes. The development of DNA molecular computer and cell biological computer has become an important part of nanotechnology.
The main content of nanotechnology
Nanotechnology is a comprehensive subject with strong cross-cutting, and its research content involves the vast field of modern science and technology. Nanotechnology mainly includes:
Nano-system physics, nano-chemistry, nano-material science, nano-biology, nano-electronics, nano-machining, nano-mechanics, etc. These seven relatively independent and interpenetrating disciplines and three research fields: nano-materials, nano-devices, nano-scale detection and characterization. The preparation and research of nano-materials are the basis of the whole nano-technology. Among them, nano-physics and nano-chemistry are the theoretical basis of nano-technology, and nano-electronics is the most important content of nano-technology.
From 65438 to 0993, the first international nanotechnology conference * * * INTC * * was held in the United States, which divided nanotechnology into six branches: nano-physics, nano-biology, nano-chemistry, nano-electronics, nano-processing technology and nano-metrology, which promoted the development of nanotechnology. Because of its particularity, magic and universality, this technology has attracted many excellent scientists all over the world to study it hard. Nanotechnology generally refers to the technology of materials, design, manufacture, measurement, control and products with nanometer scale of * * * 0./-100 nm * *. Nanotechnology mainly includes: nanoscale measurement technology: nanoscale surface physical and mechanical properties testing technology: nanoscale processing technology; Preparation technology of nanoparticles; Nanomaterials; Nanobiotechnology; Nanoassembly technology, etc.
Nanotechnology includes the following four main aspects:
1. Nano-materials: When the substance reaches the nanometer level, that is, about 0. 1- 100 nanometer, the properties of the substance will suddenly change and special properties will appear. This kind of material, which is not only different from the original atoms and molecules, but also different from the macro, is called nano-material.
If only nano-scale materials have no special properties, they cannot be called nano-materials.
In the past, people only paid attention to atoms, molecules or space, and often ignored this intermediate field, which actually existed in nature in large quantities, and did not realize the efficiency of this scale before. Japanese scientists were the first people who really realized its efficiency and introduced the concept of nano. They prepared ultramicro ions by evaporation in 1970s. By studying its efficiency, they found that a kind of conductive copper-silver conductor lost its original properties after being made into nano-scale, and it was neither conductive nor thermally conductive. The same is true of magnetic materials, such as iron-cobalt alloys. If the size is about 20-30 nanometers, the magnetic domain will become a single magnetic domain, and its magnetism is 1000 times higher than the original. In the mid-1980s, people formally named this kind of materials as nanomaterials.
Why does the magnetic domain become a single magnetic domain, and its magnetism is 1000 times higher than the original one? This is because the arrangement of single atoms in a magnetic domain is not very regular, but there is a nucleus in the middle of a single atom surrounded by electrons, which is the reason for the formation of magnetism. However, after becoming a single magnetic domain, the single atoms are arranged regularly and show strong magnetism to the outside.
This characteristic is mainly used to manufacture micro-motors. If the technology is developed for a certain period of time and used to manufacture magnetic levitation, a faster, more stable and more energy-saving high-speed train can be manufactured.
2. Nano-dynamics: mainly micro-machines and micro-motors, or micro-electromechanical systems, which are used as micro-sensors and actuators for transmission machinery, optical fiber communication systems, special electronic devices, medical and diagnostic instruments, etc. It adopts a new technology similar to the design and manufacture of integrated appliances. The feature is that the parts are very small, the etching depth often needs tens to hundreds of microns, and the width error is very small. This process can also be used to manufacture three-phase motors, ultra-high-speed centrifuges or gyroscopes. In the research, micro-deformation and micro-friction at quasi-atomic scale should be detected accordingly. Although they have not really entered the nanometer scale at present, they have great potential scientific and economic value.
Theoretically, micro-motor and detection technology can reach nanometer level.
3. Nano-biology and nano-pharmacology: for example, using colloidal gold with nano-particle size to fix dna particles on mica surface, using interdigital electrodes on the surface of silicon dioxide to carry out experiments on the interaction between biomolecules, carrying out double-layer planar biofilm of phospholipids and fatty acids, and fine structure of dna. With nanotechnology, you can also put parts or components into cells through self-assembly to form new materials. About half of the new drugs, even the fine powder of micron particles, are insoluble in water; But if the particles are nano-sized, that is, ultrafine particles, they can be dissolved in water.
When nano-organisms develop to a certain technology, nano-biological cells with recognition ability can be made of nano-materials, and the biomedical absorption of cancer cells can be injected into the human body for targeted killing of cancer cells. * * * This is an old money increase * * *
4. Nano-electronics: including nano-electronic devices based on quantum effect, optical/electrical characteristics of nanostructures, characterization of nano-electronic materials, and atomic manipulation and assembly. The current trend of electronic technology requires devices and systems to be smaller, faster, colder and smaller, which means faster response. Being colder means that a single device consumes less power. But smaller is not infinite. Nanotechnology is the last frontier of builders, and its influence will be enormous.
The potential harm of nanotechnology
Like biotechnology, nanotechnology also has many environmental and safety problems, such as whether it can avoid the natural defense system of organisms, whether it can be biodegradable and how toxic and side effects are.
Social harm
The harm of nanoparticles
Nanomaterials * * * Materials containing nanoparticles * * * are harmless in themselves. Only some aspects are harmful, especially their mobility and enhanced responsiveness. Only when some aspects of some nanoparticles are harmful to organisms or the environment can we face real harm.
In order to discuss the impact of nanomaterials on health and environment, we must distinguish between two types of nanostructures:
Nano-sized particles are assembled on substrates, materials or devices, such as nano-composite materials, nano-surface structures or nano-component electronic and optical sensors. Also known as immobilized nanoparticles.
"Free" nanoparticles, whether stored in some production steps or directly using a single nanoparticle.
These free nanoparticles can be nano-sized single elements, compounds or complex mixtures, such as "coated" nanoparticles or "core-shell" nanoparticles with one element coated with another substance.
It is generally accepted that although we need to pay attention to materials with fixed nanoparticles, free nanoparticles are the most urgent concern.
Because nanoparticles are so different from nanoparticles in daily life, their harmful effects cannot be inferred from the known toxicity. It is of great significance to discuss the effects of free nanoparticles on health and environment in this way.
More complicated, when we discuss nanoparticles, we must know that powders or liquids containing nanoparticles are almost never monodisperse, but have many different sizes in a certain range. This will make the experimental analysis more complicated, because large nanoparticles may have different properties from small nanoparticles. Moreover, nanoparticles tend to polymerize, and polymerized nanoparticles have different behaviors from single nanoparticles.
health problem
There are four ways for nanoparticles to enter the human body: inhalation, swallowing, absorption from the panel, intentional injection during medical treatment or release from implants. Once in the human body, they are highly mobile. In some cases, they can even cross the blood-brain barrier.
The behavior of nanoparticles in organs is still a big topic to be studied. Basically, the behavior of nanoparticles depends on their size, shape and interaction with surrounding tissues. They may lead to "overload" of phagocytes that devour and destroy foreign bodies, thus causing defensive fever and reducing the body's immunity. They may accumulate in organs because they cannot degrade or degrade slowly. Another worry is their potential danger of reacting with some biological processes in the human body. Due to the huge surface area, nanoparticles exposed to tissues and liquids will immediately adsorb the macromolecules they encounter. For example, this will affect the regulation mechanism of enzymes and other protein.
environmental problems
The main concern is that nanoparticles may cause unknown harm.
social risk
The use of nanotechnology also has social risks. At the instrument level, it also includes the possibility of applying nanotechnology in the military field. * * * For example, implants or other methods of equipping soldiers studied at the Institute of Soldiers' Nanotechnology at the Massachusetts Institute of Technology, and monitoring methods enhanced by nanodetectors.
On the structural level, critics of nanotechnology point out that nanotechnology has opened a new world controlled by property rights and companies. They point out that just as biotechnology's ability to manipulate genes is accompanied by patents on life, nanotechnology manipulators bring patents on substances. In the past few years, obtaining nano-scale patents is like a gold rush. In 2003, more than 800 nano-related patents were approved, and this number is increasing every year. Large companies monopolize a large number of patents for nano-scale inventions and discoveries. For example, two big companies, NEC and IBM, hold the basic patent of carbon nanotubes, one of the cornerstones of nanotechnology. Carbon nanotubes are widely used and are expected to play a key role in many industrial fields, from electronics and computers to reinforcing materials, to drug release and diagnosis. Carbon nanotubes may become the main industrial trading materials to replace traditional raw materials. However, when their uses expand, anyone who wants to manufacture or sell carbon nanotubes, regardless of the application, must first purchase a license from NEC or IBM. Content of nanotechnology