Metal-oxide gas sensors based on self-adapted temperature modulation

A self-adapted temperature modulation was proposed to study gas sensing properties by analyzing the process of the temperature role on the performance of metal oxide gas sensors.The working principle of the self-adapted temperature modulation was presented,a closed-loop circuit connecting the sensor resistance to the sensor heater was designed and temperature response curves of sensors in different kinds of gas were obtained by circuit simulaiton.Different kinds of gas had unique temperature response curve formed by the same number of pulses but with different lengths.Using hydrogen as an example,the sensor temperature range was 140-220 ℃,the temperature pulse cycle was 800 ms,the upper semi-period was 300 ms and the down semi-period was 500 ms.It provided many information about sensor response for the qualitative analysis of gas species and gas concentrations.