Wrinkled reduced graphene oxide humidity sensor with fast response/recovery and flexibility for respiratory monitoring

Respiratory health monitoring technology has a high value in medical application, but also has a broad prospect and great development space. Because of the high humidity of human exhaled gas, humidity sensor has become a very potential way in respiratory monitoring. However, most of the traditional humidity sensors are rigid structures, which can not adapt to the soft and curved human surface, and the response and recovery speed is slow, which makes it very limited in respiratory monitoring. Therefore, this paper proposes a flexible humidity sensor based on wrinkled reduced graphene oxide by pre-stretching the flexible substrate. On the one hand, the wrinkled structure of reduced graphene oxide improves the response and recovery speed of the humidity sensor. It has been experimentally proved that wrinkled structure can inhibit water aggregation and condensation. This may be the reason for the increased response/recovery speed of the humidity sensor. On the other hand, the wrinkled structure of reduced graphene oxide also makes the humidity sensor flexible, whose resistance and response/recovery speed almost remains the same under different deformation curvatures. The fast response/recovery speed and flexibility of this wrinkled reduced graphene oxide humidity sensor make it suitable for human surface and can be worn on the human body for respiratory monitoring.