Ozone sensors based on WO3: a model for sensor drift and a measurement correction method

The use of a tungstic oxide semiconductor as a sensor for ozone at concentr ation levels relevant to atmospheric monitoring applications is an importan t advance in attempts to produce cheap, lightweight and reliable instrument s. Problems of stability are a possible obstacle to this application. A mod el that describes the response of these sensors to ozone is proposed here a nd using it an explanation for the drift of resistance with time at constan t concentrations of ozone is given. Consideration of this drift model enabl es a measurement routine to be employed that compensates for the drift obse rved experimentally, thus producing a reliable calibration of the sensor.