Wearable sensing technologies are vital for realizing personalized health monitoring. Noninvasive 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 sweat 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 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 for H 2 O 2 sensing. This research enables full-body spatiotemporal mapping of sweat, which is beneficial for a broad range of personalized monitoring applications, such as drug abuse detection, athletics performance optimization, and physiological wellness tracking.

A laser induced forward transfer printed graphene/nickel composite electrode for high areal specific capacitance supercapacitor applications.

The development of renewable energy schemes requires the scalable production of highly robust electrocatalysts using a sustainable synthesis process that does not generate toxic liquid wastes. Here, an industrial laser system is utilized to prepare electrocatalysts in a continuous fashion using a laser-induced-forwardtransfer-assisted nanomaterial preparation (LANP) method without generating liquid wastes. This dry processing method at room temperature and under ambient pressure enables the production of well-dispersed Pt, Ru, and Ni nanoparticles (NPs) supported on a few-layer graphene carbon framework. This versatile LANP procedure allows for the efficient deposition of binder-free Pt, Ru, and Ni NPs onto flexible polyimide films and glass surfaces at a rate of 400 mm/s. The size and quantity of the spherical NPs present on the conductive carbon surface can be tuned by adjusting the LANP parameters such as the laser power, the scribing speed, and the source thickness. Upon increasing the laser power, the size of Pt NPs decreases and the amount of Pt in the laser-derived materials increases. A second laser treatment can further modulate the hydrophilicity and solvent accessibility of graphenesupported Pt NPs. Our results demonstrate that the binder-free Pt, Ru, and Ni NPs supported on a few-layer graphene generated using the LANP strategy can serve as practical, active, and robust electrocatalysts for water-splitting reactions in advanced electrolyzer technology.

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