Flexible Strain–Temperature Dual-Modal Smart Patch Based on 3D Printing for Wound Healing Promotion and Health Monitoring

For patients with open joint wounds, postoperative rehabilitation requires real-time and reliable monitoring of physiological parameters. Conventional elastomer- and textile-based wearable sensors often suffer from mechanical mismatch, limited breathability, or insufficient conformal adhesion, restricting their long-term use on wound sites. Although hydrogel-based sensors offer improved tissue compatibility, their practical application is challenged by dehydration and limited gas permeability associated with bulk structures. Here, we present an application-oriented hydrogel sensing platform designed to address these challenges through the integration of established material and structural strategies. A dehydration-resistant hydrogel system is constructed using a water/glycerol binary solvent and electrolyte to maintain long-term hydration and sensing stability (>1000 h). To improve breathability and mechanical compliance, a mesh-structured hydrogel sensor is fabricated via 3D printing. The fabricated sensor demonstrates good biocompatibility, promotes wound healing, and enables dual-mode strain and temperature sensing with reduced cross-interference under the tested conditions. It exhibits a gauge factor (GF) of 2.4 within the strain range of 47.5–135% and a temperature coefficient of resistance (TCR) of −4.2% °C–1 over the temperature range 22–32 °C. Integrated into a wireless smart patch and combined with machine learning, the system allows real-time monitoring and classification of rehabilitation movement patterns. This work demonstrates a system-level, application-driven integration for wearable monitoring with promising extended-use potential.