Influence of operation temperature instability on gas sensor performance

Gas sensors based on the semiconducting metal-oxides, such as SnO2, have been found to be very useful for detecting a wide range of gases. The reversible interactions of the gas with the surface of the sensing layer made of semiconducting metal-oxides are responsible for changes of sensor resistance which is usually used as a measure of sensor response. Semiconductor gas sensors are commercially available and applied in numerous gas detection systems. They are reliable, small, rugged and inexpensive. However, there are a few problems limiting the wider use of such sensors. Semiconductor gas sensor usually exhibits a low selectivity, a drift and low repeatability of the response, strong influence of temperature and moisture on sensor properties. Instability of operating temperature is one of the factors that influence sensors response and should be taken into consideration during real life measurements. In this work some experimental results demonstrating how ambient temperature affects sensor operating temperature are presented. An approach to stabilize sensor temperature by controlling sensor heater voltage have been proposed. All measurement are performed with dedicated measurement stand consisting of few bench measuring instruments.