Thermo-adaptive gelatin-based hydrogel skin patch with switchable mechanics and adhesion for on-demand wearable sensing

Abstract

To address the challenges in smart patches and electronic skins, such as balancing reliable adhesion with painless removal and reconciling mechanical performance with multifunctional integration, this study developed a multifunctional thermo-responsive gelatin-based hydrogel patch (Gel/PAA/PDA@Ag/CTAB) through synergistic molecular design. By leveraging the temperature-dependent properties of gelatin structure and multiple dynamic interactions, the system enabled intelligent and reversible switching of mechanical properties and interfacial adhesion between 4 °C and 37 °C. At 37 °C, the hydrogel exhibited high stretchability (fracture strain of 980%) and strong adhesion (25.66 kPa on porcine skin). At 4 °C, its adhesion strength decreased by more than threefold while the modulus increased modestly, facilitating gentle and painless removal. Furthermore, the hydrogel demonstrated excellent self-healing capability, high conductivity, and significant strain sensitivity (GF = 13.55), enabling stable monitoring of human motion across multiple body regions.Integration with a signal transmission system and a CNN-based algorithm allowed for gesture-based emergency communication recognition with an accuracy exceeding 90%. This work provides novel materials and integration strategies for developing intelligent thermo-responsive patches that combine "strong adhesion-easy removal" with "sensing-communication" capabilities, offering broad potential for applications in flexible bioelectronics, smart health monitoring, and human machine interaction.