Dual-parameter sensing theory for high-precision protein concentration detection with THz metasurfaces

Protein concentration detection (PCD) has been extensively used in clinical diagnostics and biopharmaceutical fields. Recently, compared with traditional PCD methods, terahertz (THz) detection has garnered widespread attention due to its advantages of being label-free, non-invasive and non-ionizing. However, current THz protein detection techniques rely on single-parameter sensing theory, which ignores the effect of temperature on protein concentration, resulting in relatively low detection precision. Consequently, in this paper, a dual-parameter sensing theory that considers both protein concentration and temperature is proposed. Based on this theory, a dual-BIC THz metasurface sensor is designed, and the transmission spectra, physical mechanism, structural parameters and sensing characteristic of the device are theoretically investigated using the full-vector finite element method. The results indicate that the refractive index sensitivities and temperature sensitivities for A-mode and B-mode are 159 GHz/RIU, 41.2 kHz/°C and 316 GHz/RIU, 24.4 kHz/°C, respectively. When the sensor is applied to PCD, the calculations reveal that the relative error is reduced by two orders of magnitude using our proposed theory, as compared to the single-parameter sensing theory. In summary, the dual-parameter sensing theory offers a fundamental theoretical framework for achieving high-precision PCD, and the dual-BIC metasurface structure serves as an ideal device for this purpose.