Terahertz metamaterial biosensor based on open square ring

In this paper, a terahertz metamaterial biosensor based on the resonant structure of the open square ring is designed, and its simulation and testing are carried out to reveal the absorbing performance and sensing performance of the sensor. The results show that the sensor can produce an extremely narrow absorption peak (absorption of 98.7%) at the resonant frequency of 0.635 THz and a half-wave width of 8.02 GHz. The best absorbance was obtained when the analyte thickness was 30 μm and the opening width was 10 μm. Under that condition, the absorption peak of the sensor showed an apparent redshift as the analyte’s refractive index increased from 1.0 to 1.8. Additionally, the sensor quality factor is 79.26, and the sensitivity is 91.5 GHz/refractive index unit (RIU). Furthermore, the sensor is prepared by UV lithography and tested. It is found that the sensor is highly sensitive to the object with a small refractive index difference and has good sensing performance. The above analysis shows that the terahertz metamaterial biosensor based on the open square ring structure prepared in this study has the advantages of simple structure, high-quality factor, and high refractive index sensitivity. It has potential applications in the field of label-free high-sensitivity biomedical sensing. Graphical Abstract Metamaterial absorber with continuous dielectric layer microcavity structure based on open array resonant ring cells.