A multichannel electrochemical all-solid-state wearable potentiometric sensor for real-time sweat ion monitoring

There is considerable interest in wearable potentiometric ion sensors that can provide information about the quality of a person's health by monitoring ion concentration levels in biofluids. Significant progress has been achieved, particularly in device integration. However, the crucial interfacial water layer and the use of transducer materials remain challenging. Herein we report a paper-based, flexible, all-solid-state, ion-selective electrode (ISE) for the real-time analysis of sweat. The super-hydrophobic paper matrix was modified with a fluorinated alkyl silane to reduce the water-layer effect. We used a high-quality graphene suspension with high conductivity and capacitance as an ion-to-electron transducer, which further stabilized the potential. The integrated solid ISE has four channels that can detect K+, Na+, Cl- and pH simultaneously. This wearable potentiometric sensor has reliable accuracy, good potential stability and low detection limits, and could be used in healthcare and clinical analysis.