Reliability studies of highly sensitive and specific multi-gas sensor based on nanocrystalline SnO2 film

We had reported the real time detection of NH3, H2S and NO2—each with specific transient response, using nanocrystalline thin film SnO2 sensor at room temperature in presence of other interfering gases, with sensitivity required for air quality monitoring. To ensure the reliable and continuous operation of the room temperature SnO2 thin film sensor, further sensing studies have been carried out under various deleterious conditions such as high humidity, in presence of various gas dissociation products and aging. The sensor did not show any change in the response towards high humidity levels up to 97% suggesting the reliability of the sensor. While SnO2 sensor showed recovery at room temperature with carrier gas flow after exposure to NH3 and H2S, NO2 required heating up to 70 °C for gas desorption. To explore the room temperature gas desorption possibilities after NO2 exposure, deNOxification studies using NH3 injection was carried out. It showed only a transient effect on the sensor recovery. Sensitivity studies over a period of one year towards NH3 gas indicated the same sensitivity with an increase in response and recovery time indicating the durability of the sensor.