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 design has been developed. These are intended for operation in the range 200-500-degrees-C and for use in array form with a gas or odour discrimination system. Following a burn-in period of 2 to 3 days, sensor drift in clean air was found to be low, with an average change in baseline resistance of less than 1% over 1 week. A substantial improvement in power consumption has been achieved for these devices, compared to conventional tin oxide sensors, through implementation of a novel thermal design. Characterisation has been undertaken using a microcomputer-controlled mass-flow system. Sensitivity measurements on two gases, namely CO and CH4, have been performed. Additional studies have looked at the response time and repeatability of these sensors. The implications of these latter results are discussed.