Quartz Crystal Microbalance Humidity Sensors Based on Nanodiamond Sensing Films

A novel quartz crystal microbalance (QCM) humidity sensor using nanodiamond (ND) as sensing films has been presented in this paper. For evaluating the performance of ND-coated QCM humidity sensor, a series of humidity-sensing experiments were carried out by using both oscillating circuit and impedance analysis methods. Based on the large specific surface area and high mechanical modulus, the ND-coated sensor exhibited large humidity-sensing response and good stability. In addition, the resultant sensors displayed low hysteresis, good repeatability, and short response time. The influence of the depositing amount of ND on the sensor's performance has also been discussed. The result indicated that the stability of QCM humidity sensor showed an extreme decrease when the deposition amount of ND on QCM is large enough. The possible reason for this anomalous phenomenon is analyzed and discussed. This study suggests that ND could be a promising candidate material for developing high-performance QCM humidity sensor.