The present study examines the operational functionality of conventional Kretschmann configuration-based surface plasmon resonance (SPR) sensor using silver (Ag) as a plasmonic material, under different refractive index (RI) conditions of the sensing medium. Additionally, this investigation explores the impact of including a silicon (Si) layer in the sensor configuration. The obtained numerical findings indicate a notable augmentation in the magnitude of the reflectance dip’s depth, referred to as sensitivity, as a consequence of including a Si layer in the analyzed structures. The use of a thin coating of Si onto the conventional structures results in optimal sensitivity, characterized by a minimal reflectivity (Rmin) of 14.5 ×  \(10^{ - 4}\) a.u and resonance angles (θres) below 80° for both configurations. The structures’ sensitivity under consideration, namely the Ti + Ag structure, is measured at 60°/RIU. Similarly, the Ti–Ag–Si structure has a sensitivity of 120°/RIU. The reported sensors, that have been suggested, possess the sensitivity to identify changes in the sensing medium with a sensitivity as low as 0.005 refractive index units (RIU). Hence, this study exhibits great potential and offers a novel pathway within the realms of medical biology and chemistry, as inferred from the obtained results.