Dew point measurements using montmorillonite (MTT) and molybdenum disulfide (MoS₂) coated QCM sensors

Due to the influence of temperature, the traditional quartz crystal microbalance (QCM) dew point sensors require an independent study on the temperature frequency characteristics (TFC) for calibrations as the frequency response is susceptible to external interferences. QCM dew point sensors with either montmorillonite (MTT) or molybdenum disulfide (MoS₂) coatings together with a dew point recognition algorithm are demonstrated for dew point recognitions. The frequency signals output from three kinds of QCM sensors are processed by the proposed recognition algorithm and compared with the standard dew point data provided by MICHELL S4000. The results show QCM sensors with MTT coating have the best accuracy and repeatability test for 5 days in range of 3 ℃ DP–15 ℃ DP environment has shown the maximum relative error as compared with the standard dew-point values is less than ±0.3 ℃ DP. As such, this work shows the feasibility of utilizing QCM humidity sensors without the influence of temperature on frequency measurements with good repeatability.