Fully Flexible Humidity Sensor with Fast Response and High Responsivity Based on rGO/MoS₂ for Human Respiration Monitoring and Nontouch Switches

Abstract

Humidity sensors have been widely used to monitor humidity in daily life, agriculture fields, and so on. However, conventional sensors are not suitable for wearable devices because of their large dimensions and rigid substrates. Hence, we report a fast response, highly sensitive, and fully flexible humidity sensor on a PI substrate based on the composite material of reduced graphene oxide (rGO)/MoS₂, with a response time of 0.65 s and a sensitivity of 96.7% in the relative humidity range of 11% RH-95% RH. A fully flexible wearable device was realized by integrating the prepared flexible humidity sensor with a flexible printed circuit, which was successfully applied for human breathing monitoring, motion monitoring, and nontouch switches. These results show that the rGO/MoS₂ composite is a good candidate for humidity sensing and has the potential to be used in the fields of wearable devices and nontouch switching.