Electrodeposited ZnO thin film on twin sensor QCM for Sensing of Ethanol at Room Temperature

QCM is one of major sensing methods for volatile organic compounds (VOC), however, the method is affected by environments such as temperature, humidity, and airflow. To cancel the signals affected by environments, we used twin sensor QCM which has two electrodes on one quartz substrate. In fact, one Au electrode was used as a reference, and ZnO thin film was electrodeposited on the other electrode to detect ethanol. The surface morphology of ZnO was changed corresponding to the applied potential on the electrodeposition. Scaly surface was obtained at -0.8 V vs. Ag/AgCl. QCM with scaly ZnO surface showed high frequency change on exposing to ethanol gas.