Surface Plasmon Resonance Gas Sensors Using Au-WO3-x Nanocomposite Films

Surface plasmon resonance (SPR) of metal-dielectric composite films formed by noble metal nanoparticles embedded in a dielectric is very sensitive to the changes in the refractive index of the dielectric induced by physical absorption or chemical reactions and is therefore exploited for gas sensing applications. In this study, Au-WO_3-x nanocomposite thin films were fabricated by pulsed laser deposition and the content of Au in the composite films was varied by altering the relative laser ablation time on Au and WO₃ targets. The SPR response of the Au-WO_3-x films in ambient atmosphere is measured for various gold percentages. The experimental results were compared to the theoretical calculations by both Maxwell-Garnett and Bruggeman effective medium theories. The SPR response of Au-WO_3-x films exposed to NO gas was measured. The preliminary results indicated that gas sensing using the SPR responses of metal-dielectric composite films is feasible.