A new type of fast dew point sensor using quartz crystal without frequency measurement

Aiming at solving the problem of atmospheric humidity measurement, a new dew point sensor using quartz crystal without frequency measurement has been developed. The sensor is composed of the Peltier module and the quartz crystal. When active condensation begins to occur in the quartz crystal surface, the electrical characteristics of the quartz crystal will change. Consequently, the oscillation characteristics of the resonant circuit containing the quartz crystal will also change. Hence, the oscillation characteristics change can be used to identify the time of condensation. The cessation of oscillation was measured, due primarily to signal attenuation caused by dew formation. This method uses the sensitive properties of quartz crystal but with no frequency measurement and also exploit the stability of the circuit. The sensor we have developed has fast response time and recovery time, especially with excellent dehumidifying performance. The accuracy of the dew point sensor when compared with the MICHELL S4000 dew point meter is found to be ±0.3 °C DP in the range of −20 °C to 20 °C DP. The low-cost sensor is easy to carry and has certain corrosion resistance.