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

Abstract

To address the long-standing dilemma in smart patches and electronic skins, specifically, the trade-off between reliable adhesion and painless removal, as well as the difficulty in reconciling mechanical performance with multifunctional integration, this study developed a multifunctional thermo-responsive gelatin-based hydrogel patch (Gel/PAA/PDA@Ag/CTAB) through a synergistic molecular design strategy. The core innovation laid in leveraging the temperature-dependent conformational transition of gelatin triple helices to achieve reversible, on-demand switching of mechanical properties and interfacial adhesion. At 37 °C, the hydrogel exhibited high stretchability (fracture strain of 980%) and strong adhesion (25.66 kPa on porcine skin), ensuring secure attachment for long-term sensing without detachment. At 4 °C, rearrangement of the gelatin triple helix markedly enhanced hydrogel stiffness, while encapsulation of active groups by the triple helix weakened interfacial adhesion and peel strength, enabling 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 a systematic strategy 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.