Humidity sensor based on quartz tuning fork coated with sol–gel-derived nanocrystalline zinc oxide thin film

This paper describes an application of quartz tuning forks (QTFs) coated with nanocrystalline ZnO films used as relative humidity sensors. The nanocrystalline ZnO thin films were deposited on the QTFs by a sol–gel method. The film was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to obtain the information on the structural and morphological properties. And the humidity sensing characteristics of the sensors have been investigated. Ethanol and acetone interference on the sensor performance have been also tested. Sensing experiments were examined by measuring the resonance frequency shift of QTFs due to the additional mass loading. The results showed that the sensors had high humidity sensitivity, good stability, fast response time and well reproducibility. We demonstrated here a simple and low-cost humidity sensor using the QTFs.