▎ 摘　　要

In this work, functionalized graphene films with different oxygen contents were prepared and their humidity sensing properties, such as humidity response, humidity hysteresis, dynamic response and recovery, were studied by combining them with a bulk acoustic wave sensor. The experimental results revealed that the humidity sensing properties of the functionalized graphene films were strongly associated with their oxygen content. The humidity response of the sensor could be improved by increasing the oxygen content of the functionalized graphene films. The stability of the sensor was also investigated using an impedance analysis method. The results indicated that the stability of the sensor was also influenced by the oxygen content of the functionalized graphene films during humidity detection. An increase in the oxygen content of the functionalized graphene film reduced the sensor stability. Thus, our work suggests that the oxygen content of functionalized graphene films is a key parameter for the design of graphene-based bulk acoustic wave humidity sensors. (C) 2015 Elsevier B.V. All rights reserved.