This paper presents a design and optimization of a multilayer surface plasmon resonance (SPR) biosensor to monitor refractive index variations associated with cadmium (Cd²⁺) ions in aqueous samples. The study examines the thickness of the silver (Ag) plasmonic layer and the effectiveness of changes in refractive index to optimize the sensor performance. The most important key performance parameters, such as sensitivity, figure of merit (FoM), detection accuracy (DA), and resonance stability, were considered. The sensor uses an FK51A prism, cadmium sulfide (CdS), carbon disulfide (CS₂) layers of high dielectric, and the 2D materials. The angular interrogation and transfer matrix method was used to analyze sensor performance at a wavelength of 633 nm for small refractive index variations (1.333–1.334). The optimized design achieved a baseline sensitivity of 256.3 °/RIU and a maximum sensitivity of 384.4 °/RIU, with a figure of merit (FoM) of 92.97 RIU⁻¹ and a penetration depth of 425.13 nm. In practical applications, selective cadmium detection would require appropriate surface functionalization.
Gurramkondu et al. (Mon,) studied this question.