Odour mapping using microresistor and piezo-electric sensor pairs

Vapour sensors were produced by electrodeposition of poly(pyrrole) using different counter-ions onto both quartz crystal microbalance (QCM) electrodes and separate interdigitated microelectrodes. The ratio of the relative change of resistance to that of frequency on exposure to a vapour was measured and was found to be independent of vapour concentration over a wide range, but characteristic of the vapour for a given polymer. The multi-property measurement results have shown the feasibility of distinguishing odourants and mixtures using a significantly lower number of different types of sensing material.