Terahertz Metasurface Multidimensional Biosensor Based on Quasi-Bound States in the Continuum for Trace Analyte Detection

The integration of terahertz (THz) technology with metasurfaces (MSs) has opened new horizons for the development of highly sensitive biosensors. In this study, we present a novel THz symmetry-protected bound states in the continuum (SP-BIC) MS-based biosensor designed to detect trace biomolecules. Added silver nanoparticles (AgNPs) can interact with THz waves to achieve local electric field enhancement, which enhances the interaction between THz waves and analytes, thereby improving the detection ability of the MS sensor. The results of the experiment showed that the MS sensor with added AgNPs achieved a frequency shift of 35.61 GHz when detecting taurine at a concentration of 111.12 ng/mL and a transmission change of 14.96% when detecting taurine at a concentration of 1.12 ng/mL. The limit of detection (LOD) of the MS sensor is as low as 20 pg/mL. The MS sensor proposed in this article features a simple structure, convenient detection, and high sensitivity, which can detect biomacromolecules and small biomolecules and demonstrate potential application value in the field of THz biological detection.