Dew point measurement using a sensitive circuit type of dew point sensor

Received: 13 Mar. 2012; Revised 25 Jul. 2012; Accepted 04 Aug. 2012 Received: April 8, 2012; Revised May 4, 2012; Accepted June 6, 2012 Abstract: Aiming at the problem of atmospheric humidity measurement, this paper proposes a method to measure dew point based on sensitive circuit for the first time. We use the quartz crystal in the Colpitts circuit as the humidity sensitive element. Since the Colpitts circuit cannot drive quartz crystal oscillate in liquid environment, we use Peltier element to cool the quartz crystal until the dew is generated when the quartz crystal is in the liquid phase environment. The Colpitts circuit oscillation stops when the condensation occurs. At the same time it gets the temperature of quartz crystal surface when vibration stops so as to recognize and measure the dew point. Through the analysis of referenced data and experimental data, it is proved that the proposed method can be used for identifying the validity and accuracy of humidity from the qualitative point. The results are important and have practical significance for further quantitative analysis, research and development of sensitive circuit type dew point instrument.