A fully wearable conductive yarn-based sweat sensor powered by shoe insole-based TENG

Abstract

The rise of wearable technology has transformed personalized healthcare and wellness, allowing for continuous monitoring of essential analytes in bodily fluids, especially sweat. This study introduces a self-powered approach utilizing solid-contact ion-selective electrodes (SC-ISEs) for non-invasive sweat analysis and triboelectric nanogenerators (TENG) for energy harvesting from mechanical motion, addressing the critical need for personalized hydration strategies for athletes. By developing cotton yarn-based potentiometric sensors for sodium ion detection integrated into a silicone microfluidic sweat patch, we ensure optimal skin contact and accurate sweat sampling, which are the usual challenges associated with traditional substrates. Furthermore, we present an innovative self-powered system that incorporates a shoe insole-based TENG (siTENG), capable of harvesting energy from the wearer’s biomechanical motion. The siTENG is the first of its kind to be fully characterized on-body and is capable of producing an impressive peak power density of around 110 mW m−2 while stepping on it at an ultra-low frequency of 0.5 Hz. The integration of yarn-based SC-ISE’s with siTENG not only enhances the sensor’s usability by eliminating reliance on bulky batteries but can also provide real-time monitoring of sweat sodium levels during physical activity. This system offers a novel, self-powered solution for real-time monitoring of sodium levels in sweat, that can potentially aid athletes and sports practitioners in optimizing hydration strategies for enhanced performance.