Stability and Control of a Metal Oxide Gas Sensor in Simulated Wind

Semiconducting metal oxide gas chemical sensors show promise for applications in handheld and personalized air quality monitoring systems. One limitation of these sensors is their cross-response to outdoor factors, such as temperature and humidity fluctuations. Previously, airflow (e.g., wind) was known to modify sensor output, but the cause of this response was not greatly characterized. In this paper, we investigate the effect of airflow on the output of a commercial metal oxide sensor in dry and humid air. Upon exposure to a step in airflow, the output of these sensors increases by more than 6% over 1 h. We also control the temperature of the sensor's embedded heater resistor using an external proportional-integral controller. With this control, the sensor output after exposure to airflow increases by <1% over 1 h, demonstrating a stabilization scheme for air quality measurements that does not require additional temperature sensing equipment.