Vertically Aligned Gold Nanowires as Stretchable and Wearable Epidermal Ion-Selective Electrode for Noninvasive Multiplexed Sweat Analysis

The noninvasive continuous analysis of human sweat is of great significance for improved healthcare diagnostics and treatment in future, for which wearable potentiometry based Ion-selective electrode (ISE) has attracted increasing attention, particularly involving ion detection. Note that traditional solid-state ISE electrodes are rigid ion-to-electron transducer that is not conformal to soft human skin and cannot function under stretched states. Here, we demonstrated that vertically aligned mushroom-like gold nanowires (v-AuNWs) could serve as stretchable and wearable ion-to-electron transducer for multiplexed, in-situ potentiometric analysis of pH, Na+ and K+ in sweat. By modifying v-AuNWs electrode with polyaniline, Na ionophore X and valinomycin based selective membrane, we could specifically detect pH, Na+ and K+, respectively, with high selectivity, reproducibility and stability. Importantly, the electrochemical performances could be maintained even under 30% strain and during stretch-release cycles...