Preparation and Characterization of Nanoporous Gold Film Based Surface Plasmon Resonance Sensor

Au-Ag alloy films of around 60 nm thickness are deposited on the slab glass substrate by radio frequency sputtering technique. Then large-area uniform nanoporous gold films (NPGF) with strong adhesion are fabricated by chemical dealloying at room temperature. The resonance spectrum of NPGF exposed to the air in the visible-near-infrared region is obtained by a self-built broadband spectral surface plasmon resonance (SPR) detection platform. The Fresnel formula and Bruggeman dielectric constant approximation equation are used to fit the experimental results. The porosity of NPGF is about 0.38. The response characteristics of the NPGF-SPR sensor to Pb²⁺ ions and melamine molecules adsorbed from the individual aqueous solutions with different concentrations are investigated. The experimental results show that the NPGF-SPR sensor can make obvious responses to both Pb²⁺ ions and melamine molecules in the aqueous solution with 1 nmol·L^-1 concentration. The comparison experiment shows that the NPGF-SPR sensor is much more sensitive than the conventional SPR sensor with a dense gold layer.