A fast response and highly sensitive flexible humidity sensor based on a nanocomposite film of MoS 2 and graphene oxide.

Graphene oxide (GO)-based humidity sensors are attracting widespread attention due to their high responsivity and low cost. However, GO-based humidity sensors generally suffer from slow response and recovery as well as poor stability. Here, we report a flexible resistive humidity sensor based on a MoS ₂ /GO composite film that was fabricated by mixing different volumes of MoS ₂ and GO dispersions with adjustable volume ratios. The MoS ₂ /GO composite film has been used as a sensing layer on screen-printed interdigital electrodes. The results show that the best device performance was achieved at a dispersion volume of 0.05 mL with a MoS ₂ /GO volume ratio of 5 : 1, featuring a high responsivity (∼98%), a fast response/recovery time (1.3/12.1 s), excellent stability and low cost. Furthermore, the humidity sensor exhibits good linearity over a wide humidity range (33%RH-98%RH) at room temperature (25 °C) and can be fabricated easily and feasibly. The application of the humidity sensors we prepared in human respiration detection and human fingertip proximity detection has been demonstrated. These findings indicate the great potential of the MoS ₂ /GO composite in developing next generation high-performance humidity sensors.