A novel method of temperature compensation for a stable combustion-type gas sensor

Abstract

A novel application method of combustion-type gas sensor mainly for thermally decomposable gas determination and a scheme to compensate the temperature dependence is suggested. In this method, a pair of heat detecting devices which have same physical and chemical property are utilized. These devices are driven with different currents. One for gas detection is operated at above the thermal decomposition temperature with larger current, and the other for compensation, reference device, at below the corresponding temperature. As ambient temperature varies, the resistances of a detecting device and a reference one vary, as well as their terminal voltages. Unlike a bridge configurated devices, the reference device exhibits smaller temperature dependence. Amplification of the reference signal with appropriate gain and subtracting of the amplified reference signal and the detecting device signal could compensate the ambient temperature variations. The method is successfully applied to ozone detection with excellent stability. A prudent design of the sensor chamber demonstrates good immunity against gas flow rate variation. But change in thermal conductivity of the detecting gas is not compensated with the present method.