Liquid Refractive Index Sensor Based on Terahertz Metamaterials

Diabetes is one of the biggest health problems in the world; in order to control blood in modern biological detection and analysis, most of them use the method of label determination to realize the detection. This method usually needs to modify and label the samples in advance. This pretreatment process is not only complex, time-consuming, and slow in response, but also has a great risk of damaging and polluting the samples to be tested, which seriously limits the detection accuracy [1, 2]. In order to realize the real-time detection and analysis of biological targets without label, high precision, and high sensitivity, the design of liquid refractive index sensor based on terahertz metamaterials is carried out in this paper. Based on terahertz technology and artificial periodic structure design of metamaterials, a liquid refractive index sensor with high precision, high sensitivity, and high stability is successfully designed. Then, based on the equivalent medium theory, the absorption characteristics of the sensor are studied; it is proved that the sensor has excellent polarization-insensitive and wide-angle incident characteristics. It can complete the detection of biological targets in most polarization modes and electromagnetic wave environment with various incident angles, and maintain perfect absorption at the resonance frequency of the sensing structure. The displacement of the resonance absorption peak is 102 GHz, the displacement sensitivity is 51 GHz/RIU, and the detection accuracy is 0.0196 RIU/GHz, which can realize the detection of minimal refractive index change; the average absorption index is high, which is 99.98%, and the displacement of absorption peak has an excellent linear relationship with the change of refractive index, and the linear fitting degree is 98.788%. Through data analysis, it is found that the sensor structure also has a strong bandwidth and absorption stability, which has a certain practical application value in the detection and analysis of biological targets. It provides a new idea for the real-time detection and analysis of biological liquid analytes with no label, high precision, and high sensitivity. Finally, through the data analysis, the change law of the sensor absorption characteristics with different physical dimensions is revealed, which lays a theoretical foundation for the future sensor structure optimization and the improvement of sensing accuracy and sensitivity.