High Performance Humidity Fluctuation Sensor for Wearable Devices via a Bioinspired Atomic-Precise Tunable Graphene-Polymer Heterogeneous Sensing Junction

Measurements of an individual's water metabolism dynamical information can provide us rich biological information in a noninvasive way. This concept is hindered by the trade-off between the sensitivity and responsive velocity of traditional moisture sensors. Herein, inspired by the molecular detecting system based on weak bond interactions in natural organisms, we designed a new concept of a tunable graphene-polymer heterogeneous nanosensing junction by confining a reasonable thickness sensing material into graphene nanochannels. The fundamentally new sensing mechanism based on dynamical hydrogen bonds endows the sensor with over 4 orders of magnitude sensitivity toward a wide range of relative humidity (RH) (from 0% to 97%) with unprecedented fast response (20ms) and recovery times (17ms) with little humidity hysteresis. The promising advantages of the sensor allow us to record humidity fluctuation information in real time during a user's speech and breath, which can both reveal the speech feature and monitor the respiration rate accurately. Importantly, this advanced sensor provides a new opportunity for accurate and reliable physiological and psychological monitoring by detecting the subtlest RH fluctuations on human skin in a noncontact way