The selectivity of a chemiresistive gas sensor comprising an aligned array of single-crystalline tin oxide nanowires (NWs) is shown to be greatly enhanced by combined temperature and gate voltage modulation. This dual modulation was effected by utilization of a novel microsensor platform that consisted of a suspended nitride membrane embedded with independently addressable platinum heater and back-gate structures. The sensor was evaluated in a training/recognition task with three volatile organic compound analytes (ketones and alcohols between the concentration range of 20 μmol/mol to 80 μmol/mol) in an air background. The dual modulation of temperature and gating was utilized in the NW sensor in order to modify its surface transduction mechanisms and to thus increase the amount of analytical information provided by its chemical response. Standard pattern recognition techniques were used to evaluate the extent that this approach improved selectivity. A high recognition accuracy of 98 % was achieved only through the combined cycling of temperature and gate bias as compared to the modulation of one of these parameters alone. The good selectivity shown in these results demonstrate the potential for miniature nanowire sensors to tackle real-world, multi-chemical detection problems.
Pub Type: Journals
Tin oxide nanowires, gas discrimination, microhotplate, suspended silicon nitride membrane, FET sensor, nanowire field-effect transistor (FET), volatile organic compounds