Design and Electromagnetic Analysis of a TMDC-Assisted Multilayer SPR Optical Biosensor with Ultra-High Angular Sensitivity for Brain Tumor Screening and Early Detection

Cancer-related brain tumors require highly sensitive diagnostic platforms for early-stage detection; however, conventional MRI and CT imaging techniques often exhibit limited sensitivity for identifying tumors at ultra-early stages. To address these limitations, this study presents a highly sensitive surface plasmon resonance (SPR) biosensor based on the Kretschmann configuration integrated with transition metal dichalcogenides (TMDCs). The proposed multilayer structure comprises a BK7 prism, an optimized 47 nm Ag layer, ultrathin TMDC layers (MoS 2 , MoSe 2 , WS 2 , and WSe 2 ), and a Si 3 N 4 dielectric spacer supporting the sensing region. Electromagnetic analysis using Maxwell’s equations and the transfer matrix method (TMM) demonstrates enhanced plasmon–exciton coupling and strong electric-field confinement. The optimized MoSe 2 -based configuration achieves a maximum sensitivity of 788.945°/RIU, a FOM of 464.358 RIU −1 , a DL of 0.001 RIU, and a maximum electric-field intensity of 1.22 × 10 5 V m −1 at a resonance angle of 71.2°. The obtained results confirm the effectiveness of TMDC-assisted multilayer architectures for nanoscale refractive-index sensing, establishing a promising platform for advanced biomedical diagnostic applications including rapid brain tumor screening and early detection.