Silver Thickness Optimization for Sensitivity Enhancement in a Surface Plasmon Resonance Biosensor for Multi-Cancer Detection

This work proposes a highly sensitive Surface Plasmon Resonance (SPR) biosensor for label-free refractive index (RI) and biological sensing applications based on a BK7 prism-coupled bimetal (Ag/Au) and Tantalum Diselenide (TaSe2) hybrid structure. The transfer matrix method (TMM) is used to examine the sensing performance of the suggested structure while accounting for the effects of various biological sensing media (SM) and plasmonic layer thickness. To attain optimal plasmonic coupling, the impact of Ag layer thickness on sensitivity and minimum reflectance (Rmin) is methodically examined. For the long RI range of 1.35–1.40, the maximum sensitivity is 206.32°/RIU at the Rmin value. Depending on the sensing layer, the Ag thickness ranges from 39 to 42 nm, offering better resonance properties for various cancer detection. Basal, HeLa, Jurkat, PC12, MM-231 and MCF-7 have remarkable Rmin values and the highest sensitivity of 260.49°/RIU, 280.13°/RIU, 290.24°/RIU 260.49°/RIU, 280.13°/RIU and 290.24°/RIU with an optimized Ag thickness of 42–39 nm among the biological layers under investigation, respectively. Moreover, the penetration depth (PD) of 192.94 nm and 181.5 nm is attained at RIs of SM 1.35 and 1.40. The suggested SPR biosensor is a promising platform for biosensing, disease diagnosis, and real-time monitoring applications because of its exceptional sensitivity, low resonance reflectance, and improved detection capability.