Selectivity enhancement of tin dioxide gas sensor with polymer membrane

The application of a polymer to enhance the selectivity of a tin dioxide gas sensor is presented. Commercial polymer, XU218 of Ciba-Geigy company, is coated on the sensing film of a tin dioxide gas sensor FIGARO TGS842 which was designed to detect methane. The polymer coated sensor is calibrated in a high accuracy testing chamber that is controlled by PC with GPIB and mass flow controllers (MFCs). Three gases, hydrogen, methane, and ammonia, are used to investigate the response of the sensor. It is found that the sensor shows a characteristic change in response to ammonia and almost negligible change in response to hydrogen and methane.