An electrochemical sensor with both antifouling and self-cleaning strategies for uric acid detection in sweat

Sweat sensing faces a critical barrier in the form of biofouling caused by shed keratinocytes and hydrophobic sebaceous oils in the epidermal environment. These contaminants form insulating layers that disrupt electrical contact, cause signal drift, and compromise sensor reliability. While zwitterionic antifouling strategies mitigate protein adsorption, they are less effective against this combined assault. Herein, a low-fouling and self-cleaning electrochemical sensor was developed for sweat analysis. The sensor was constructed through the modification of a screen-printed electrode with reduced graphene oxide based polypeptide hydrogel (rGO/PEPG/SPE) and a hydrophilic TiO₂/PVDF-based multilayer. A hydrophilic TiO₂/PVDF nanofilter blocking keratinocytes and resisting oily accumulation while enabling biomarker diffusion. A conductive rGO/PEPG sensing layer providing zwitterionic antifouling properties to proteins, bacterias, etc. In addition, embedded TiO₂ nanoparticles provide photocatalytic self-cleaning. UV light triggers in situ generation of reactive oxygen species (ROS) that mineralize accumulated oils into CO₂ and H₂O, enabling sustained sensor functionality. Validated by detecting uric acid (UA) in undiluted human sweat, our sensor achieves accuracy rivaling ELISA. By synergizing size-exclusive filtration, molecular antifouling, and active self-regeneration, this work establishes a new paradigm for reliable wearable sweat diagnostics.