Surface plasmon resonance gas sensor with a nanoporous gold film

Abstract

This work demonstrates an optical gas sensor based on the surface plasmon resonance (SPR) of nanoporous gold (NPG) thin films. The NPG films are prepared by a sputtering-dealloying combined method, and they can support the propagating surface plasmon mode and adsorb a large number of gaseous molecules; the interaction of the internal plasmon field and the adsorbed molecules enables the NPG-SPR sensor to have high sensitivity. The Kretschmann-type spectral NPG-SPR sensor is fabricated with a 60-nm-thick NPG film, and its spectral response to toxic H2S gas was investigated at room temperature. The optimal sensitivity of the sensor to H2S was achieved by controlling the dealloying time to tune the film porosity. Comparison of the spectral sensitivity to 100 ppm H2S indicates that the NPG-SPR sensor is at least six times more sensitive than a conventional Au-SPR sensor.