Gas sensor using high-frequency quartz crystal microbalance

Fundamental modes (9 & 50 MHz) and overtone modes of 3rd mode of 33 MHz (100(3) MHz) and 5th mode of 20 MHz (100(5) MHz) of quartz crystal microbalances. (QCMs) with high frequencies are studied to increase the frequency response of QCM gas-sensor. On the fundamental and overtone modes, the ratio of mass sensitivity of QCMs calculated from theory is consistent with that of the experimental results.