A Fouling-Resistant Voltammetric Sensing System for Wearable Electroactive Biomarker Monitoring

Voltammetry-based sensing systems are suitable for wearable monitoring of electroactive biomarkers in epidermally-retrievable biofluids (e.g., sweat), as they can directly transduce the redox features of the targets into electrical signals, delivering a sample-to-answer solution. To render reliable voltammetric readouts, the fundamental challenge of biofluid-induced fouling (causing rapid and irreversible signal degradation) must be addressed-an issue which has been overlooked in the previously reported wearable sensor development methods, but widely reported in conventional voltammetric platforms. To this end, here, we devise a fouling-resistant voltammetric sensing interface that exploits an inert electrode surface (specifically, boron-doped diamond, facilitating weak adsorption of polar molecules) as well as a hydrophilic membrane coating (chitosan) to mitigate the interaction of fouling agents with the surface. Utilizing this engineered sensing interface, sub-micromolar level quantification of uric acid was demonstrated, where the sensor presented minimal interference from non-target electroactive species (within their physiologically relevant concentration range). By interfacing the developed sensor with a wireless circuit board-augmented with a dedicated analytical framework-seamless uric acid readout acquisition in sweat was achieved. The presented biofouling characterization/mitigation methodology provides a basis for wearable electroactive sensing system development.