A vapor sensor array using multiple localized surface plasmon resonance bands in a single UV–vis spectrum

This research reports a sensor array consisting of three types of surface-modified nanoparticles that exhibit localized surface plasmon resonance (LSPR) extinctions at different wavelength regions of a UV–vis spectrum. By simultaneously measuring the ensemble of the LSPR bands of the three nano-materials, response patterns were obtained at different regions of a UV–vis spectrum. Three types of nano-metals used in this study were Ag nanoparticles, Au nanoparticles and Au nano-shells. The center wavelengths of their LSPR bands were 427, 534 and 772 nm respectively, after they were each modified with decanethiol, naphthalene thiol and 2-mercaptobenzothiazole to create chemical selectivity. The average absolute difference in the absorbance of each LSPR band was used as the signal for each sensor. Reversible, rapid (∼8 s) and wide linear range responses were observed with this sensor array. Nine volatile organic compounds (VOCs) with various functional groups were tested with this sensor array and differentiable groups of response patterns were obtained. The detection limits were as low as 16 ppm for anisole.