Study Of Terahertz Metamaterials For High-sensitivity Biosensors

Terahertz（THz）waves have low energy,high resolution and strong absorption properties,and many biological macromolecules exhibit strong resonance absorption in the terahertz band,making terahertz waves ideal for use in biological testing and medical research.Metamaterials are artificially designed materials with a periodic structure that can be modulated by changing their structure,and weak changes in the refractive index of the surrounding environment can cause significant changes in the electromagnetic properties of metamaterials.The combination of terahertz technology and metamaterials has potential application and development in the field of biosensing.Based on this,the research on terahertz metamaterials high sensitivity biosensors is carried out in this thesis,and the main research contents are as follows.Two types of dual-band terahertz metamaterial sensors based on continuous and discontinuous dielectric layers are proposed.The sensing characteristics and absorption mechanism of the two metamaterial sensors with different dielectric layer morphologies were investigated.The results show that the refractive index sensitivity of the dual-band metamaterial sensor with a continuous dielectric layer is 91.7GHz/RIU at the resonant frequency f₁ and 105.1 GHz/RIU at the resonant frequency f₂,while the refractive index sensitivity of the dual-band metamaterial sensor with a discontinuous dielectric layer is 159.6 GHz/RIU at the resonant frequency f₁ and196.8 GHz/RIU at the resonant frequency f₂.The refractive index sensitivity at the two absorption peaks was improved by 74.05%and 87.25%for the discontinuous layer compared to the continuous layer metamaterial sensor.In order to further improve the sensitivity of the sensor and achieve direct detection of liquid samples,a terahertz metamaterial biosensor with an integrated microfluidic channel is proposed,which produces a perfect absorption peak at 0.5293THz.The simulation results show that the refractive index sensitivity of this metamaterial sensor is 225.85 GHz/RIU.Considering that the sensor with a single absorption peak is weak against interference in practical applications and can easily lead to a decrease in sensing accuracy,a dual-band terahertz metamaterial sensor with an integrated microfluidic channel is proposed,where the sensor forms two perfect absorption peaks at 0.7672 THz and 0.9296 THz.The refractive index sensitivities of the high-frequency absorption peak and the low-frequency absorption peak are360.27 GHz/RIU and 398.80 GHz/RIU,respectively.The two resonant peaks are able to exhibit different degrees of frequency shift in the sensing application,which can bring differentiated information to the measured material,thus enhancing the sensing accuracy and sensitivity.