Humid Test Comparision of Nano ZnO with HMDS on the QCM

QCM-based gas sensors are potential for applications due to its simple structure and high sensitivity.But the low selectivity attributed to the environment factors such as the variations of humidity,volatile organic vapors(VOCs) need to be concerned.This paper divided into two sections,first,the sensing properties of nano zinc oxide were studied by quartz crystal microbalance(QCM) in relative humidity detection.The results showed that the nano zinc oxide film had high humidity sensitivity and good reproducibility.Second,the humidity sensing properties of nano zinc oxide treated by HMDS(Hexamethyl disilazane) were also investigated. It is found that the humidity sensitivity of nano zinc oxide treated by HMDS was much lower than untreated ZnO,especially in high relative humidity environment.The further study indicated that the nano ZnO treated by HDMS was more sensitive to organic gases,such as ethanol,but less sensitive to humidity.It indicates that the HMDS treated nano ZnO can be used to detect organic gases in high relative humidity environment with improved selectivity.