| For thousands of years,the evolutionary history of human civilization is a history of material technology at the same time.From the simple application of stone tools to skilled use of iron and copper smelting technology,to mastered complex semiconductor technology and nanotechnology.The smaller the scale of materials used in the development of human civilization,the more complex the process and the more powerful the function.Although semiconductor technology and nanotechnology have very powerful functions and are applied to all aspects of human life,from the perspective of development,these technologies can no longer meet the needs of current human development.In recent years,the field of physics materials has turned its attention to new materials which designed by hand,such as meta-materials,stealth materials and photonic crystals.Especially for meta-materials,meta-materials are new materials which are different from traditional materials.They have special artificial structures and some special physical properties that natural materials do not have,such as zero refractive index and negative refraction.This paper mainly studies the materials that have derivative and integral functions for biological light information and acoustic information,stealth functions for living organisms,and photonic crystal materials that can be used to make various types of bio-sensors.First,optical meta-materials that can perform derivative and integral operations on the optical information of biology are studied.Using the gradient index material can perform Fourier transform on the light wave,an optical meta-material with a three-layer structure is designed,and the two sides are gradient refractive index materials respectively performing Fourier transform and inverse Fourier transform.The intermediate is a material with complex refractive index.The structural size and physical properties of the material are obtained through theoretical analysis.The theoretical and numerical simulation results show that the meta-materials can perform the first derivative,second derivative,and integral operation of the contour of the biological light signal by changing the refractive index of the intermediate material under the condition that the refractive index of the materials on both sides is constant.Moreover,theoretical analysis and numerical simulation also show that there is no difference between the two in the case of normal incidence,whether it is positive refractive index or negative refractive index.In this case,all negative refractive index in the model can be replaced with positive refractive index.The same computing function can still be achieved.The model is simpler than the original model,and the materials used can all be positive refractive index materials.The specific innovations are as follows:(1)The model is simpler,the input and output ends are not in the middle of the two gradient refractive index materials,so that the signal can be directly input from the left side and output from the right side.In addition,there is no air layer above and below the material,which can reduces the error by reducing the reflection of the interface.(2)The materials used are more common.In our model,the sides can be positive refractive index materials,and the refractive index of the intermediate materials can also be positive.(3)Using the relationship between permittivity,magnetic permeability and refractive index,the refractive index is used to describe the properties of the material,and the single condition is more easily satisfied than the two conditions in the experiment.On the basis of the three-layer structure meta-materials,the intermediate layer in the three-layer structure is deleted according to the law of the Helmholtz formula satisfying the electric field strength of the electromagnetic wave in the medium,and the physical properties of the intermediate material are superimposed on both sides.It can simplify the three-layer structure into a two-layer structure.The results show that the two-layer structure can also achieve the same function as the three-layer structure.The simplification of the structure is one step forward in the experimental implementation of the computational function meta-materials.When an electromagnetic wave propagates in a medium having a gradient refractive index,the gradient refractive index material performs a Fourier transform on the incident wave.Because sound waves and electromagnetic waves obey the Helmholtz formula when they propagate in the medium,sonic waves have similar properties to electromagnetic waves.When sound waves propagate in acoustic materials with gradient sound velocity,gradient sound velocity materials can also perform Fourier transform on sound waves.The method and idea of realizing the optical signal computing function of the living body by using optical meta-materials,using the sound velocity to describe the acoustic properties of the material,theoretically constructing an acoustic meta-material that can perform the first derivative and the second derivative operation on the biological acoustic signal.The acoustic meta-materials may be a three-layer structure,or the three-layer structure may be simplified into a two-layer structure by a method of fusing the function of the intermediate material into the two-sided material.Whether it is optical computing meta-material or acoustic computing meta-material,whether it is a three-layer structure or a two-layer structure,graphics images or sounds can be processed quickly,if applied to bio-graphic analysis,graphics storage or sound analysis and storage,it will greatly improve the speed and ability of graphics processing.Secondly,related research is carried out on the stealth cloak with stealth function of the living body.The static magnetic cloak is realized by the topological insulating material and the NdFeB permanent magnet material.The two magnetic cloaks are composed of two hollow cylinders made of topological insulating material and NdFeB permanent magnet material with different permittivity and inherent magnetization.When a uniform magnetic field is applied to the double hollow cylinder,The expression of the magnetic potential of each region can be obtained by the Laplace formula,and the magnetic field distribution of each region is obtained from the gradient relationship between the magnetic field strength and the magnetic potential.According to the magnetic field distribution condition of the magnetic cloak:The outer region should still an external magnetic field,that is,a uniform magnetic field,and there should be no magnetic field distribution in the inner cylinder.The size,natural magnetization,relative permittivity and relative permeability of the topological insulator and the NdFeB permanent magnet material satisfying this condition are obtained.Theoretical and numerical simulation results show that the double-loop structure of the two materials can make the magnetic induction line enter the cylinder and surround the cylinder.The shielding area has no magnetic field distribution,and the magnetic field after passing through the double-layer cylinder is still a uniform magnetic field.Finally,the photonic crystals materials that can be used to make various types of bio-sensors are studied.The photonic crystals are periodic structures composed of materials with different permittivity and scales.The appearance of photonic band gaps is mainly determined by the permittivity proportional relationship and the geometric configuration of the photonic crystal.The band gap of the one-dimensional and two-dimensional photonic crystal can be adjusted by changing the permittivity of a material through changing the temperature(time)or illumination without changing the structure and material of the photonic crystal.One-dimensional photonic crystals are constructed with pure water and glass.Because the relative permittivity of pure water changes with temperature,so the band gap of the photonic crystal changes with temperature as the temperature changes,The law that the band gap changes periodically with time(temperature)is obtained.A two dimensional photonic crystals is constructed using CCTO,because CCTO has electro-optic effect,when CCTO is irradiated with light of different intensity,The refractive index of CCTO changes.According to this principle,the band gap of the two-dimensional CCTO photonic crystal is adjustable.The law that the band gap changes periodically with time is obtained.At the same time,a two-dimensional photonic crystal is formed by using a gallium arsenide elliptical cylinder,and the relative permittivity of gallium arsenide is not changed,but the photonic crystal band gap can also be adjusted when the gallium arsenide is rotated,and the law of periodic variation of band gap with time is obtained.Based on the constructed tunable photonic crystal,the bio-sensors for measuring the concentration of water temperature,NaCl,Fe,Zn,Diquat and other solutions are designed,and the relationship between the concentration(temperature)and the center wavelength(frequency)of the transmission peak of the photonic crystal is obtained.This type of bio-sensors has many advantages such as fast,low cost,visualization and reuse.It has laid a certain theoretical foundation for its practical application.Through the study of optical and acoustic meta-materials with derivative and integral operations for biological and acoustic information.Meta-material with three-layer and two-layer structures are constructed,and the physical properties and structural dimensions of the materials required to achieve the corresponding functions are obtained.The structure has been greatly simplified,and it will play a certain role in promoting the research in this field in the laboratory.Through the study of the topological insulation material and NdFeB permanent magnet material with stealth function of the living body,the magneto-static cloak of the size and relative permittivity,relative permeability and natural magnetization of the material of the static magnet cloak are obtained.The magnetic cloak is not a superconducting material or a super material,and the structure is relatively simple.In particular,NdFeB is a very common and easily available material;This will greatly facilitate the design and implementation of its design.Through the study of photonic crystals which can be used to make bio-sensors,one-dimensional photonic crystal and two-dimensional photonic crystal are constructed by using common materials such as water,CCTO and gallium arsenide.Temperature,light intensity and the rotation angle are used to control the band gap of the photonic crystal.At the same time,the adjustable photonic crystal is applied to the bio-sensor to measure various trace elements and toxic and harmful substances. |
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