Ultrahighly Sensitive QCM Humidity Sensor Based on Nafion/MoS<sub>2</sub> Hybrid Thin Film
Xiang Yu, Xiangdong Chen, Xinglin Yu, Xinpeng Chen, Xing Ding, Xuan Zhao, Kung Tang
Abstract
In this article, a Nafion/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> hybrid thin film was deposited on quartz crystal microbalance (QCM) for detecting humidity, in which moderate MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanosheets with small size were dispersed into a Nafion membrane to improve its humidity sensitivity. The experimental results indicate that a hybrid film QCM humidity sensor with the best volume ratio of Nafion/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> exhibits a considerably higher shift frequency (−11 879 Hz) than a pure Nafion film QCM humidity sensor, even more than most of the reported QCM humidity sensors. It could be that the molybdenum disulfide nanosheets dispersed in the Nafion film would form some nano-assembly near the hydrophilic group of Nafion, which greatly enhances the ability of the composite film to establish water channels, thus promoting hydrophilicity of the composite film. The highly sensitive humidity sensor could clearly distinguish tiny humidity difference near the back and palm of a hand. Therefore, it has potential application in human–robot collaboration.