Nanotechnology comes into life

  In December 1959, physicist Richard Feynman gave a speech entitled “Ample Space at the Bottom”. His theme was “The problem of manipulating and controlling things at a tiny level.” In this speech, Feynman was not satisfied with the technique of engraving letters on the needle (which was already very cutting-edge technology at the time). He asked: “Why can’t we write the entire encyclopedia on the needle?”
  He gave the answer to this question: We are not trying to make the letters smaller to engrave, but to manipulate the atoms of the needles themselves to form letters, and nanotechnology is formally proposed. In 1990, for the first time, the letter “manipulating” the atomic manipulation was used. The English letter “IBM”, which shared 35 atoms, realized Feynman’s vision.
  Since the advent of nanotechnology, it has been defined as the “world of tomorrow”, which has been described in hundreds of science fiction novels. But in fact, the industrial revolution of nanotechnology has quietly emerged, and in some areas has begun to show their talents. So, what is the difference between nanotechnology and how will it change our world?
  What is nanotechnology?
  Nano is a unit of length, but this unit is very small, only one billionth of a meter. It’s hard to feel how small a nanometer is. Imagine a hair that is 75,000 nanometers and a DNA double strand that is about 2 nanometers wide.
  The so-called nanotechnology is to change the connection structure of atoms to create a new molecule under controlled conditions. Nanotechnology produces different types of nanoscale materials (composed of nanoparticles) with nanoparticle sizes ranging from 1 to 100 nanometers.
  At the beginning of the 20th century, people began to prepare nanoparticles of metals and their oxides by evaporation. In the middle of the 20th century, people explored the mechanical pulverization method to refine the material particles. Nowadays, the methods for preparing the nanoparticles are mainly divided into two major categories: chemical methods and physical methods.
  Physical methods are generally “top-down”, that is, physical methods are used to destroy relatively large substances into nanoscales, and these nanoscale small units are converted into suitable nanoparticles. The physical method is divided into a pulverization method and a construction method. Among them, the pulverization method mainly adopts a method of grinding, crushing, etc.; the construction method includes a gas evaporation method, a mixed plasma method, and the like.
  The chemical method is mainly a “bottom-up” method of preparing nanoparticulate matter from molecules and atoms by appropriate chemical reactions (including liquid phase, gas phase and solid phase reaction). The chemical synthesis method includes a gas phase reaction method and a liquid phase reaction method, and the most commonly used methods include a sol-gel method, a redox method, a gas phase decomposition method, a gas phase synthesis method, and the like.
  Nanoparticles extraordinary characteristic
  macroscopic technique large construction material blocks arranged in the microchip, sports car, oak table and skyscrapers and a relatively rough approximation model. Nanotechnology, on the other hand, can manipulate individual atoms and take human technology to the next level.
  The most important thing about nanoparticles is that they are extremely small in size, but at the nanoscale, the properties of the material can vary greatly. Because we are faced with a single atom or molecule rather than a mass of matter, quantum effects are the most important factor here. For macroscopic substances, the nature of matter does not change regardless of shape and size, but for nanoscale materials, the area-to-volume ratio and relative size change, and the properties of the substance also change.
  For example, nanoparticles often have unexpected optical properties because nanoparticles can limit their electrons and produce quantum effects, such as gold nanoparticles that appear magenta in solution. Nanoparticles can form a suspension because the interaction of the surface of the particle with the solvent is strong enough to overcome the difference in density; if it is a non-nano material, this interaction usually causes the material to sink or float in the liquid. The uneven distribution of electrons in the nanoparticles leads to magnetic properties, and magnetic nanoparticles have attracted the interest of researchers in different disciplines. The unique mechanical properties of nanoparticles are also used in many important areas, including elastic modulus, hardness, stress and strain, adhesion and friction.
  By changing the size and shape of things at the molecular level, scientists can tailor the properties of nanoparticles to specific purposes. For example, “nanowires” have a diameter of only 1 nanometer, thus limiting the flow of electrons over their width, and the conductivity of the nanowires can be precisely controlled. The “quantum dot” has a thickness of 1 atom and a diameter of 50 atoms, and the diameter can be adjusted and controlled. Because of its physical shape, quantum dots convert ultraviolet light into visible light at a specific frequency, and the frequency of the emitted light changes as the size of the quantum dot changes. A nanotube is a cylinder made up of a layer of 1 atom thick carbon. Rolling tubes at different angles, reaching different diameters, can change their mechanical, electrical, thermal and optical properties. Among all the materials found so far, this structure means that these pipes have the highest tensile strength and are more than 100 times stronger than steel.
  Nanotechnology has entered the daily life
  and now we have entered a place where everybody uses, nanotechnology needs of the times. The nanotechnology described in many early science fiction novels has been implemented in a way that we are not aware of, such as it is a component material for smartphones or other devices, but we don’t know that these are based on nanotechnology. . Nanotechnology has quietly penetrated into every aspect of our lives and is part of our daily lives.
  Today, from sunscreens, clothing, cars, sunglasses to computers and displays, the use of nanotechnology is everywhere, even in the most everyday life. For example, sunscreens typically contain nanoparticles of titanium dioxide (TiO2) and zinc oxide (ZnO), both of which are highly UV absorbers. Some clothes also add titanium dioxide and zinc oxide to protect against ultraviolet rays, while adding silica nanoparticles to the clothes for waterproofing, and silver nanoparticles for antibacterial. In 2016, Chinese researchers also used the same principle to make a cloth that does not block ultraviolet light but absorbs ultraviolet light and converts it into electricity. Similarly, researchers at the University of California invented an invisible cloth that uses gold nanoparticles to redistribute the light around the object to achieve an invisible effect.
  As we gain a deeper understanding of nanoengineering, nanotechnology will have more impact on what we produce. For example, we are expanding the application of nanotubes. Like nanotubes, quantum nanotubes are now exploring its medical applications, not only in diagnostics and drug delivery, but also because they can be used as “nano sponges.” Nanotubes are quickly and naturally excreted in the human body. Therefore, when used as a nanosponge, it attaches toxins in the blood and carries the toxins out of the body.
  Similarly, researchers are also exploring nanotubes to clean up oil spills and purify water. Nanotubes are combined with contaminants and then removed using filters tailored specifically for their nanostructures. Future trends in nanotechnology will include: nanobots, nanosensors, cancer research, genetics and medicine, hydrophobic materials, food and agriculture.
  Risks of nanotechnology
  Nanotechnology in our lives has been widely used, so the risk is more on nanotechnology brought to our attention. One of the problems is whether the nanoparticles are toxic. Earlier studies have confirmed that nanoparticles of the same material do have some toxicity compared to larger particles – some organs of mice are severely affected by nanoparticles, some aquatic After the organisms are exposed to the nanoparticles, their offspring are drastically reduced. If nanoparticles have an effect on other animals, it is likely to have a similar effect on the human body. Nanoparticles can enter the body through breathing, ingestion, skin absorption and drug injection. Once they enter the body, they can be freely transferred in the human body. The blood-brain barrier is not a barrier to some nanoparticles.
  Nanotechnology theory involves a process called self-assembly, in which molecules are stimulated to form a structure spontaneously, rather than by binding forces, stacking, and bonding. This makes us have to consider what should happen if the self-assembly process becomes uncontrollable? What if a particular carbon structure continues to self-assemble indefinitely, converting all available carbon (including you) into unused and uniform masses?
  Of course, for the above two issues, we don’t need to worry too much at the moment. Because, to a large extent, nanotechnology is the re-production of some elements that already exist in nature, under artificial control. With the in-depth study of nanotechnology, the more we understand the system, the more we learn to do things safer, and the nanoparticles we believe are most dangerous may become the most common nanoparticles in the future.