▎ 摘　　要

This paper reports a humidity detection system of quartz crystal microbalance (QCM) sensor based on layer-by-layer self-assembled poly (dimethyl diallyl ammonium chloride) (PDDAC) and graphene oxide (GO) nanocomposite film. The microstructures of the PDDAC/GO film were characterized by X-ray diffraction, Fourier transform infrared spectrum and scanning electron microscopy. The hydrophilic property of GO and PDDAC/GO composite was investigated by water contact angle measurement. The humidity sensing properties of the PDDAC/GO film-based QCM sensor were investigated upon exposure to a broad range of 0-97% RH. The experimental results showed that the presented PDDAC/GO nanocomposite sensor had a high sensitivity, a good repeatability, and fast response/recovery characteristics. Moreover, the probable humidity sensing mechanism of the PDDAC/GO film-coated QCM sensor was discussed. This paper highlights the unique advantage of layer-by-layer self-assembled PDDAC/GO for QCM humidity sensor fabrication.