Humidity sensitive properties of ZnO nanotetrapods investigated by a quartz crystal microbalance

ZnO nanotetrapods were prepared and studied for the humidity detection application. The humidity sensors developed were featured by combination of a quartz crystal as a transducer and ZnO nanotetrapods as a sensing element. The ZnO nanotetrapods were synthesized by evaporating highly pure zinc pellets (99.999%) at 900 °C in air and then distributed onto the electrode surfaces of the quartz crystal at room temperature. The synthesized ZnO nanotetrapods were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results indicated that the response of the sensors varied with the thickness of the ZnO nanotetrapods layer. The maximum frequency sensitivity was nearly ∼100 Hz/% relative humidity (RH) in the humidity range of 40-80% relative humidity (RH). The ZnO nanotetrapods sensors also had a good frequency stability and reproducibility. Thus it was found that ZnO nanotetrapods were a potential humidity sensing material.