INTEGRATED TIN OXIDE SENSORS OF LOW-POWER CONSUMPTION FOR USE IN GAS AND ODOR SENSING

A range of low power integrated thin film tin oxide sensors of novel d esign has been developed. These are intended for operation in the rang e 200-500-degrees-C and for use in array form with a gas or odour disc rimination system. Following a bum-in period of 2 to 3 days, sensor dr ift in clean air was found to be low, with an average change in baseli ne resistance of less than 1% over 1 week. A substantial improvement i n power consumption has been achieved for these devices, compared to c onventional tin oxide sensors, through implementation of a novel therm al design. Characterisation has been undertaken using a microcomputer- controlled mass-flow system. Sensitivity measurements on two gases, na mely CO and CH4, have been performed. Additional studies have looked a t the response time and repeatability of these sensors. The implicatio ns of these latter results are discussed.