Fully Self-Healing Wearable Biosensing System for On-Body Monitoring of Pulse Signals and Sweat Cortisol Levels.

Abstract

Wearable biosensors that continuously monitor physiological and biochemical stress signals are essential for understanding acute and chronic stress responses. Conventional wearable sensors often suffer from mechanical damage, unstable skin adhesion, and limited durability of biochemical sensing, which undermine long-term reliability. Here, we report a fully self-healing wearable biosensing system that integrates a laser-induced graphene (LIG) strain sensor, a molecularly imprinted polymer (MIP) cortisol sensor, microfluidic channels with cross-hatch patterned fillers, a catechol-functionalized polyurethane (CF-PU) adhesive, and an oxime-carbamate bond-based polyurethane (OC-PU) encapsulation layer for simultaneous monitoring of pulse signals and sweat cortisol levels. The LIG-based strain sensor provides pulse waveforms, while the MIP-based cortisol sensor enables selective detection of cortisol in human sweat, achieving a detection limit of 10 pM. The microfluidic channels ensure continuous sweat collection and delivery to the sensing interface, and the CF-PU adhesive maintains skin attachment in the presence of sweat. This system maintains reliable biosignal acquisition under repeated cycles of mechanical damage and self-healing at 65°C for 6 h, as well as prolonged operation. As a result, the system enables non-invasive monitoring of physiological and biochemical stress markers after mechanical damage and offers a fully self-healing stress-monitoring platform for next-generation health applications.