Advanced Terahertz Gallium Nitride Metasensor for Enhanced Molecular Absorption Spectrum Analysis of Analytes

Terahertz (THz) fingerprint metasensing is an effective method for identifying biological substances, offering advantages such as high efficiency and non-destructiveness. Currently, one important approach to achieving THz fingerprint spectrum sensing is the design of THz metasurface (MS) sensors with broad spectral coverage and multiple resonant peaks. However, there is still exhibit potential for further enhancement in the sensitivity, selectivity, and detection limits of THz sensors. Gallium nitride (GaN), with its exceptional optoelectronic properties such as high carrier concentration, high mobility, and excellent chemical stability, can be integrated with THz MSs to create high-performance sensors. In this study, we propose a THz MS biosensor coated with GaN. Since different analytes exhibit distinct absorption characteristics in the THz range, preliminary identification of various substances can be achieved by analyzing differences in the trends of spectral amplitude changes. Experimental results demonstrate that the proposed metasensor achieves a detection limit of 1 μg/mL for bovine serum albumin (BSA) and 10 pg/mL for creatinine. Through radar chart analysis, the transmission spectra of the metasensor show significant differences when detecting creatinine and BSA, indicating its capability to effectively identify different analytes. The GaN metasensor developed in this study provides a highly sensitive and broadly spectrally covered solution for THz fingerprint spectrum analysis, which holds potential applications in assessing kidney function and health status.