Development of a humidity sensor using quartz crystal microbalance

Sensitive humidity sensor using Quartz Crystal Microbalance (QCM) is presented. A humidity change is detected by an oscillation frequency change depending on the mass of the absorbed H/sub 2/O molecule. Obtained coefficient of humidity-to-frequency shift is about 0.8%/Hz. We developed a crystal oscillator type humidity sensor using a thin Cr/sub 2/O/sub 3/ film. As a basic characteristic, sensitivity was obtained in relative humidity, and it was concluded that the presented sensor can serve as a practical humidity sensor.