Ga-Sb and Ga-AgCl liquid metal-based electrodes with self-healing for sweat pH sensors

Abstract

Flexible electronic devices with self-healing ability have garnered wide attention, and the development of liquid metal-based electrodes may extend their applications. The application of self-healing electronics is challenging and has not been fully proven in a complex physiological environment. Herein, a one-step method was developed to prepare Ga-Sb and Ga-AgCl inks, which were used to fabricate pH-sensing and reference electrodes for self-healing sweat pH sensors. The Ga-Sb electrode exhibited a high pH sensitivity (62 mV pH⁻¹), small hysteresis (12 mV), excellent stability (1.5 mV h⁻¹) and selectivity. The Ga-AgCl electrode was insensitive to pH but demonstrated favorable selectivity and stability (2 mV h⁻¹), especially in solutions with halide ions. A wearable sweat pH sensor incorporating both of these electrodes offered real-time pH monitoring with excellent response performance. Additionally, these electrodes could be effectively repaired by simple heat treatment and maintained stable performance. This study provides a novel approach for developing repairable and durable wearable sweat-detecting devices.