Study of VHF-band QCM gas sensor

A VHF-band quartz crystal microbalance (QCM) gas sensor made up of a resonator with its thin quartz plate and a sensing film was studied to raise its sensitivity. The fundamental mode was used instead of the harmonic mode because of its high sensitivity. The sample flow system using a diffusion method was constructed and the experiment on the vapor exposure was performed. It was found that its sensitivity was one order of the magnitude improved when the 20 MHz resonator, the typical one was replaced by the 77 MHz one.