High Performance Refractive Index Biosensing vis-á-vis WS ₂ /Graphene Hybrid Surface Plasmon Resonance for Skin Disease Detection

This study presents a highly responsive surface plasmon resonance (SPR) biosensing platform that employs a WS 2 /graphene hybrid interface for refractive index driven identification of vitiligoaffected skin tissues, including the epidermis, dermis, collagen, keratin, and melanin layers. Comprehensive structural optimization is performed by examining the angular reflectance characteristics using the transfer matrix formalism. The configuration is numerically investigated in COMSOL Multiphysics through the wave-optics module, enabling detailed evaluation of the transverse magnetic field distribution. Simulation outcomes confirm that incorporating WS 2 with graphene substantially strengthens the electromagnetic coupling via enhanced field localization and increased penetration depth, which collectively elevate the sensing capability. Sensitivity benchmarking is conducted by tuning the number of WS 2 and graphene layers, revealing that the optimized design attains a peak sensitivity of 307.36°/RIU, quality factor of 136.79 RIU -1 . Overall, the proposed WS 2 /graphene-enhanced SPR architecture emerges as a robust, label-free, and noninvasive diagnostic tool for vitiligo sensing application.