Thickness Dependence of Sensitive Membranes on QCM to Improve Selectivity and Sensitivity in VOC Detection

In this study, we investigated the thickness dependence of QCM gas-response sensitivity to improve the sensitivity and selectivity toward VOCs emitted from engines. Hydrophilic and hydrophobic polymer films were used as sensitive membranes because different adsorption-related interactions were expected for different gases. The film thickness of each sensitive membrane was increased systematically. As a result, sensitivity improved with increasing thickness even for hydrophobic membranes or VOCs with hydrophobic functional groups when functional-group-derived interactions between the sensitive membrane and the target gas were suggested.