Sensing mechanism of polymer for selectivity enhancement of gas sensors

The sensing mechanism of polymer gas separation membrane to enhance the selectivity of tin dioxide gas sensors is presented. Two types of Commercial polymers, XU218 and PMDA-ODA of Ciba-Geigy company, are used to coat onto the sensing film of FIGARO series tin dioxide gas sensors TGS800, TGS813 and TGS842. Different gases such as carbon monoxide, hydrogen, methane, and ammonia are used to investigate the response of the sensors. It is found that the sensors show a characteristic change in response to polar gas ammonia, a relatively small change in response to slightly polar gas carbon monoxide, and almost negligible change in response to non-polar gases hydrogen and methane.