The Research Of The Stability Of MOS Gas Sensors

Eight indirectly heated ZnO based gas sensors and six TGS gas sensors have been used to test six kinds of VOCs in different humidity environment. The change tendency of the MOS gas sensor's properties according to the change of the relative humidity has been discussed. As the humidity increased, besides the MOS gas sensor's resistance and sensitivity to the reducing gas decreased, the reaction velocity of the MOS gas sensor to the reducing gas increased. The declining degree of resistance and sensitivity of the sensors when humidity changes from 0%RH to 30%RH is more obvious than the declining degree of those when humidity change from 30%RH to 60%RH and from 60%RH to 90%RH. We have explained this phenomenon according to the mechanism of the reaction .We also used the features of the sensors to discriminate the VOCs. The influence of the humidity on the steady-state and dynamic-state feature was discussed. Finally the discrimination results which used different features were contrasted. It showed that the discrimination result which used both steady-state and dynamic-state feature was the best.The stability of the ZnO based gas sensors which made by screen-printed technology has been discussed. ZnO/Cu2O gas sensors showed better stability. The stability of the sensors sintered at 700℃were better than the sensors sintered at 600℃.