Few-Layer Si and WS₂-Based Surface Plasmon Resonance Sensor for Water Salinity Concentration Detection: Theoretical Insight

This work offers a few-layer silicon (Si)-based SPR sensor with WS₂ 2D material. The silver (Ag) layer is used as plasmonic metal to generate the surface plasmon wave (SPW). The performance of the proposed sensor has been analyzed by the transfer matrix method (TMM) and finite element method (FEM). The proposed sensor obtained a maximum sensitivity (S) of 405.08°/RIU and 456.64°/RIU and a figure of merit (FoM) of 117.81/RIU at 600-nm and 633-nm wavelength. In addition, we have calculated the field intensity and penetration depth (PD) with water salinity concentration of 0% (1.33) and 30% (1.33629). The proposed few-layer Si and WS₂-based SPR sensor performed exceptionally well in detecting different concentrations of salinity in water, exhibiting remarkable sensitivity, a wide measurement range, high detection accuracy, efficiency, and dependability.