Performance evaluation of QCM dew point sensors with different wettability electrode

For accurate identification characteristics of dew point sensors based on quartz crystal microbalance (QCM), the performance of QCM with different wettability electrodes was evaluated. With the materials of 1 H, 1 H, 2 H, 2 H-perfluorodecyltrimethoxysilane (PFOTMS) and 3-(methacryloyloxy) propyltrimethoxysilane (MPTMS), and the cleaning methods of plasma and ultrasound, QCM electrodes with different wettability were prepared. The influence of wettability on dew point identification characteristics was analyzed by observing differences in the static contact angle and surface structure of each QCM, and experiments were carried out to study the frequency characteristics of each QCM. The results demonstrated that when the wettability of the QCM electrodes was lower, the dew was close to spherical and its distribution was dense, which was beneficial for accurate identification. The dew point temperature was identified by detecting the temperature of the point when the QCM frequency variation slop changed to 0, and the QCM treated with plasma-PFOTMS had excellent measurement performance as its maximum measurement error was less than 0.38 ℃DP at the dew point range of 0–14 ℃DP in five days. This study provided a new approach for optimizing high-precision QCM dew point sensors.