Design and analysis of SPR-based refractive index sensor with enhanced sensitivity based on graphene/BP heterostructure

In this article, we propose a novel surface plasmon resonance (SPR) sensor design with the combination of two-dimensional (2D) nanomaterials including copper, nickel, and graphene, along with a bonding layer of black phosphorous, to achieve significant enhancements in plasmonic performance. Theoretical analysis of the parameters has been performed using the Fresnel equations and Transfer Matrix method, based on the Kretschmann setup. For the CaF₂ Prism/Cu/Ni/Graphene/BP/Sensing-Medium configuration, the optimized performance parameters include an angular sensitivity of 410°/RIU, a detection accuracy of 0.33789^°, a figure of merit (FOM) of 138.538 RIU/deg, and a limit of detection of 2.439 for the medium being sensed at 633 nm. The utilization of both graphene and BP proves advantageous in increasing the SPR sensor's sensitivity since BP and graphene possess stronger adsorption energy, making it a more suitable candidate for actively binding biomolecules. The proposed device showcases considerable potential for the detection of large-sized molecules such as secretary vesicles and lysosomes. The numerical simulation has been performed in the COMSOL Multiphysics and MATLAB environment.