Research On Terahertz Metamaterial Sensor Based On Mie Resonance

Terahertz refers to electromagnetic waves with a frequency of 0.1-10 THz and a wavelength of 0.03-3 mm between microwave and infrared.In recent years,with the exploration of the characteristics of terahertz waves,it has potential applications in biomedicine and sensing.Metamaterial is an artificially constructed electromagnetic material or structure with extraordinary physical properties not found in natural materials.The emergence of metamaterials provides new ideas for the development of terahertz devices.The combination of their excellent characteristics has attracted much attention for terahertz metamaterial biosensor applications.This thesis mainly studies a terahertz metamaterial biosensor based on MIe resonance.The electromagnetic simulation software CST(Computer Simulation Technology)2017 microwave studio is used for simulation design and experimental preparation.The first part studies that there is no analyte to be detected on the surface of the metamaterial.When the terahertz wave passes through it,the function of the reflection coefficient and frequency is used to characterize the sensor's sensing performance.The surface pattern of the metamaterial is a circle with a periodic unit structure.The period is P = 200 microns and the diameter is D = 170 microns.When there is no analyte to be measured,the resonance frequency is 1.143 THz,the Q factor is up to 110,and high Q resonance support Strong interactions between electromagnetic waves and specific analytes.In the second part,the surface of the metamaterial is covered with the analyte to be measured,the thickness of the analyte and the value of the refractive index n are changed.The function of the reflection coefficient and the frequency is used to characterize the sensing performance of the sensor.The analyte used was a photoresist material,and the values of the refractive index n were 1,1.2,1.4,1.6,1.8,and 2.0,respectively,and the thickness was sequentially increased from 0.5 micrometers to 70 micrometers.Firstly,a thin analyte is used to cover the surface of the metamaterial,and the thickness is gradually increased from 0.5 micrometers to 20 micrometers.When the value of n remains unchanged,the resonance frequency starts to change,and it becomes more and more obvious as the thickness increases.Further increase the thickness of the analyte,the thickness gradually increased from 30 microns to 70 microns,when the value of n remains unchanged,the change in resonance frequency is more obvious than the previous step.And when the thickness of the analyte remains the same,when the value of the refractive index n increases from 1 to 2 in turn,a significant change in the resonance frequency is also found.This shows that the sensing performance of the metamaterial is affected by the thickness of the analyte and the refractive index n covering the surface.The results show that the sensor is highly sensitive to the analytes attached to it.The general supersurface sensor has low sensitivity to thick film covers,but the supersurface not only exhibits thinner analytes.Good sensitivity,and also shows high sensitivity to tens of microns thick film analytes.Finally,the super surface was prepared by micro-nano processing technology,and the problems encountered in the preparation process were given.Although the ideal super surface could not be prepared in the end,the entire experimental process still had some guiding significance,and the super surface was the fabrication of the surface provides the technical means.