This study investigates sensitivity enhancements in two optical fiber surface plasmon resonance (SPR) biosen-sor configurations: D-shaped and V-shaped designs. The D-shaped model revealed that the Ag-TiO2 combina-tion with a rectangular grating achieved the highest sensitivity of 11.7 [μm/RIU] and a detection accuracy of 1.43 × 101 μm?1. The Au-Fe2O3 combination exhibited a sensitivity of 9.33 [μm/RIU]. In the V-shaped model, silver achieved the highest sensitivity (99,000 [nm/RIU]) and detection accuracy (2.38 mm?1) at a refractive in-dex of 1.41. These findings highlight the influence of material selection on biosensor sensitivity for medical diagnostics, particularly for detecting viral infections