Analysis Of Degradation Law And Causes Of SnO₂ Gas Sensor

SnO₂ gas sensors have been widely used in environmental monitoring,such as detecting toxic gases,explosive gases,humidity and odors.Domestically produced gas sensors suffer from relatively poor reliability,stability and consistency.SnO₂ gas sensors degrade during storage and operation periods,resulting in declines in reliability,leakage,false alarms,and other problems.The leakage gas even may initiate explosion accident,resulting in irreparable loss of life and property.This paper studied SnO₂ gas sensor performance degradation during storage and operation with the help of accelerated stress tests to explore the degradation law and causes,the research achievements can provide reference for improving the reliability and stability of domestic gas sensors.In order to obtain the degradation data of SnO₂ gas sensors within a short period,accelerated degradation testing was designed.Ambient temperature and heating voltage were chosen as the acceleration stresses,constant stress loading methods were selected to conduct degradation tests under elevated temperature and voltage.In order to elucidate the degradation behavior of gas sensors,exponential linear degradation model was employed to model the degradation process under accelerated stresses,the degradation behavior of sensors under normal stresses was identified with the help of Arrhenius model and inverse power model,and then the consistency of degradation mechanisms was checked.After determining the failure threshold,the pseudo-failure time of the SnO₂ gas sensor were obtained by extrapolation,and were considered as the sensor pseudo-life data.The sensor pseudo-life distribution parameters and reliability were calculated.In order to investigate the degradation cause of the SnO₂ gas sensor,microscopic inspection and analysis of the SnO₂ gas sensor before and after the test were carried out with the aid of SEM and XRD testing methods.The analysis of the results shows that the size of the degraded SnO₂ grains increases,the increase in the sensitivity of the gas sensor is related to the increase in the number of surface micropores,and the decrease in the resistance value under clean air is related to the aggregation between the grains.