Flexible, self-healable, adhesive and wearable hydrogel patch for colorimetric sweat detection

Recent advances in wearable sweat sensors with noninvasive health monitoring capabilities have provided enormous potential for point-of-care testing (POCT) diagnostics and personalized medicine. In this paper, we present a flexible, self-healable, adhesive and wearable hydrogel patch for on-demand sweat colorimetric detection. Such a user-specific wearable hydrogel patch is simply prepared by the solvent displacement method, and can directly attach to human skin for in situ sweat sampling and colorimetric analysis without any complicated preparation steps. This wearable hydrogel patch shows excellent reliability and stability for measuring pH (4-9), glucose (0-2 mM), Cl- (0-100 mM) and Ca2+ (0-16 mM) in human sweat through integration with smartphones. The analysis and detection of multiple sweat biomarkers of 15 healthy volunteers have been successfully realized by effectively converting the analyte concentration into RGB digital signals through the wearable hydrogel patch. Such a wearable hydrogel patch with flexible, self-healable, adhesive properties can achieve on-demand in situ sweat colorimetric detection, holding great potential in point-of-care devices.