The authors of this book are Peter Forbes and Tom Grims. They mainly introduce the development of nanotechnology from three aspects: materials, strange phenomena and practical applications.
(1) nanomaterials
The important goal of nanotechnology is to develop new nanomaterials, including three valuable carbon nanomaterials-fullerenes, carbon nanotubes and graphene.
Fullerene is a kind of nanosphere formed by the interconnection of carbon atoms. 1985, Dr. Closso of the University of Sussex discovered a molecule consisting of 60 carbon atoms. Inspired by a paper by Fuller, an architect, Closso and his colleagues determined that the combination form of these carbon atoms was a sphere and named it "fullerene". Inside fullerene is a cavity. Some scholars have stuffed nitrogen atoms into the holes of fullerenes. The new materials have high electron spin lifetime and can be used to manufacture high-precision navigation equipment.
199 1 year, Japanese researcher Masao Iijima first discovered carbon nanotubes. Carbon nanotubes (CNTs) are nano-sized hollow tubes, whose walls are completely composed of carbon atoms, and their mechanical strength is very high, which can reach more than 100 times that of steel. If carbon nanotubes are made into suspension cables, they can be stretched to 5000 kilometers above sea level and even used to make cables for space elevators.
In 2004, Professor Gaim of Manchester University and his doctoral student Novoselos prepared a carbon "flake". In this small slice, the carbon atoms are connected in a hexagon, which is only one atom thick. This material is "graphene".
In order to prepare graphene, Gaim and Geim stuck a small piece of graphite between two tapes, and through repeated pasting and tearing, the number of layers of graphite was continuously reduced until a single layer of graphene was obtained. At present, graphene is the thinnest but hardest nanomaterial in the world. Its strength is 200 times that of steel, its conductivity exceeds that of copper and silver, and it is almost completely transparent. Graphene has many potential applications, such as making rapid DNA sequence detection equipment.
(2) Strange phenomena
Many strange phenomena will happen on the nanometer scale, and even have an impact on the macro world, such as "structural color" and "self-assembly".
Different from paint color, structural color is a color formed by the regulation of light by a specific microstructure. The wavelength range of visible light is about 400 to 700 nanometers. When the light shines on the structural plane of the same scale, it will produce some unique deflection or scattering, thus forming the structural color.
Structural colors are common in living things. For example, the blue of the wings of a big blue butterfly is a structural color. Observing the wings of the blue butterfly with an advanced microscope, we will find that its wings are covered with a large number of tiny tile-like structures, the size of which is in the nanometer level, and they are periodically distributed on the surface of the wings. When light strikes these tiny structures, specific refraction and reflection will occur. If the human eye observes macroscopically, it can see bright blue.
The advantages of structural color are environmental protection and not easy to fade. Many scholars are imitating and making such colors artificially. For example, some researchers use a material called elastic polymer to produce structural colors. When this material is stretched and bent, its microstructure will change, resulting in different colors. Clothes made of this material can be stretched to change color.
"Self-assembly" means that substances and systems can spontaneously form ordered structures, which is also a phenomenon that can occur on the nanometer scale.
Self-assembly is a very promising material manufacturing and device processing method. In chip manufacturing, it is necessary to use mask aligner to carve nano-scale microstructures on the wafer. In order to achieve this ultra-high precision, a mask aligner costs hundreds of millions of dollars. In order to reduce the cost of chip manufacturing, in 20 19, American researchers obtained highly regular nano-arrays through self-assembly of nano-molecules in special chemical environment. This work is considered to subvert the existing chip manufacturing methods.
(3) Practical application
In practical application, nanotechnology can be used to solve difficult problems in the fields of energy and health.
In order to cope with the energy shortage, some scholars have suggested that air can be turned into fuel through nanotechnology. For example, scientists try to develop "synthetic leaves" to simulate the photosynthesis of plants, and use air and water as raw materials to make compounds that can be used as fuels.
For "synthetic leaves", external energy and catalyst need to be introduced. The form of energy can be light energy, electric energy and other forms, with a wide range of sources; The role of catalyst is more critical, and the reaction speed needs to be improved.
At present, the most advanced research idea is to reduce the size of catalyst to nanometer level. With the same mass, the smaller the particle size, the more surface area can be exposed, which means more atomic energy can participate in the reaction. The particle size of commercial platinum catalyst is only about 3 nanometers. The research team from China Academy of Sciences successfully converted water and air into methanol fuel through nano-catalysts.
Nanotechnology can also play a great role in the health field, such as using nanotechnology to induce cell differentiation.
Stem cells can differentiate into different kinds of cells, which can be used to treat diseases and repair human injuries. How to control the differentiation direction of stem cells has always been a difficult problem. Therefore, it is necessary to study the interaction mechanism between cells and the surrounding environment.
Biologist Ingeber believes that the external force on cells will affect their behavior. He cooperated with the nano-scientist Whiteside to make bumps of different sizes on the substrate and transplant skin cells to the substrate for growth. On the large bumps of more than ten microns, the cells are uniformly stressed and grow normally; On the small bumps of several hundred nanometers, the cells are concentrated and easy to die.
This idea was introduced into the field of stem cell research. Some researchers have created nano-surfaces with different shapes to place stem cells. Among them, the star-shaped surface will make stem cells in a very tense state, and these stem cells are easy to differentiate into bone tissue; Stem cells are relatively relaxed on the flower-shaped surface, and they are easy to become fat cells; There is also a concave pattern with the size of 120 nm, which can keep the stem cells in their original state without differentiation.
The development of nanotechnology is changing with each passing day, and the new materials and technologies born from it will transform our real world like giants moving mountains and filling the sea, and make human society move towards a better future.