A wearable fluid capture device for electrochemical sensing of sweat.

Wearable sensing technologies are vital for realizing personalized health monitoring. Non-invasive human sweat sampling is essential for monitoring an individual's physical state using rich physiological data. However, existing wearable sensing technologies lack the controlled capture of body sweats and in performing on-device measurement without inflammatory contact. Herein, we report the development of a wearable sweat-capture device using patterned graphene arrays with controlled superwettability and electrical conductivity for simultaneously capturing and electrochemically measuring the sweat droplets. The sweat droplets exhibited strong attachment on the superhydrophilic graphene patterns, even during moderate exercising. The captured sweat droplets present strong electrochemical signals using graphene films as the working electrode and metal pins as the counter electrode arrays assembled on 3D printed holders, at the detection limit of 6 µM detection limit for H2O2 sensing. This research enables full-body spatiotemporal mapping of sweat, beneficial for a broad range of personalized monitoring applications, such as drug abuse detection, athletics performance optimization, and physiological wellness tracking.