Sensitivity enhancement of surface plasmon resonance sensors using 2D metallic niobium diselenide

We propose and demonstrate a surface plasmon resonance (SPR) sensor using metallic niobium diselenide (NbSe₂). A BK7/Cr/Au/NbSe₂ multilayer was modeled to investigate the layer-number-dependent sensing performance. The simulated angular sensitivity first increases and then decreases with NbSe₂ layer number, reaching 273 deg/RIU for six-layer NbSe₂ within the investigated range. X-ray photoelectron spectroscopy confirms NbSe₂ deposition on Au. Refractive-index experiments agree with the simulations and give a sensitivity of 286.38 deg/RIU for the Au/NbSe₂ structure, higher than those of bare Au, Au/BP, and Au/graphene structures. Glucose sensing shows a linear response from 10 to 500 ng/mL, corresponding to 55.5 nM to 2.78 μM, and a limit of detection of 2.73 ng/mL, corresponding to 15.2 nM. These results provide a practical strategy for high-sensitivity SPR sensing platforms based on metallic two-dimensional materials.