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 concentration levels relevant to atmospheric monitoring applications is an important advance in attempts to produce cheap, lightweight and reliable instruments. Problems of stability are a possible obstacle to this application. A model that describes the response of these sensors to ozone is proposed here and using it an explanation for the drift of resistance with time at constant concentrations of ozone is given. Consideration of this drift model enables a measurement routine to be employed that compensates for the drift observed experimentally, thus producing a reliable calibration of the sensor.