Detection of humidity by quartz crystal microbalance method using thin metal base

The sensitive humidity sensor by quartz crystal microbalance (QCM) using thin metal base is presented. A humidity change is detected by an oscillation frequency change depending on the mass of the absorbed H/sub 2/O molecules. As a basic characteristic, the sensitivities of platinum base was 2.56%/Hz in relative humidity range from 20 to 25%RH (20/spl deg/C), and 0.36%/Hz in relative humidity range from 80 to 85%RH (20/spl deg/C). Thus we conclude that platinum base is suitable material for a practical humidity sensor.