An ultra-sensitive multilayer surface plasmon resonance (SPR) biosensor based on BK7/ \(\:ZnO\)/Ag/PDA/Graphene platform is proposed and numerically characterized to detect immunoglobulin G (IgG). Angular interrogation of the structure with a wavelength of 633 nm is done using the Transfer Matrix Method (TMM) to analyse the optical performance of the structure. The optimization analysis demonstrates that the 60 nm layer of Ag gives a better sharpness of resonance and a high plasmon coupling efficiency. The relative study of three configurations shows that addition of \(\:ZnO\), PDA, and graphene improves resonance angle shift and sensitivity remarkably. Additional optimization suggests that 20 nm PDA layer is optimized to reach a maximum angular sensitivity of 237.04°/RIU, and the quality factor and signal-noise ratio is enhanced. The suggested structure has excellent performance over various conventional and prism-based SPR sensors that are 2D material-assisted. The proposed multilayer SPR biosensor is based on BK7/ \(\:ZnO\)/Ag/PDA/Graphene has a high sensitivity, sharp resonance properties, and high index of refraction, and has a high potential in real-time, label-free, and potential for high-resolution IgG diagnostics due to its high sensitivity, sharp resonance characteristics.
