Improving Optical Fiber-Based Surface Plasmon Resonance Performance Through Gold Film Modification via 3-Aminopropyltriethoxysilane Silanization

The functionalization of a gold surface with 3-aminopropyl-triethoxysilane (APTES) enhances the performance of fiber optic-based plasmonic sensors. Using the aqueous phase deposition (APD) method, APTES concentrations of 1–4% were tested. FTIR analysis showed increased amine (-NH₂) absorption with ammonium ions interacting electrostatically with Au, which improved particle rearrangement, reduced porosity, and increased surface compactness at higher concentrations. These changes enhanced the refractive index, shifted the SPR wavelength to the right, and deepened the transmittance curves. The addition of APTES significantly improved sensor performance, with sensor sensitivity increasing to 2088 nm/RIU with 4% APTES compared to 1484 nm/RIU without APTES.