Manifold sensitivity improvement of hydrocarbon odour sensors

We show that the sensitivity of swelling-based gold core-shell nanoparticle (Au CSNP) chemiresistors for vapour sensing can be enhanced considerably by cooling such sensors with respect to ambient temperature. We explain this by the increased swelling of the ligand shell at lower temperature due to the reduced volatility of the analyte. This interpretation is supported quantitatively by measurement and analysis of sensitivity at different temperatures, and to different vapours. Sensitivity to a particular vapour scales with temperature in the same way as that vapour´s saturated vapour pressure. That allows quantitative prediction of sensitivity enhancement for vapours not yet tested, as long as their enthalpy of vaporisation is known. We believe our conclusions apply to all sensors that work by swelling in analyte vapour.