Skin-inspired highly stretchable, tough and adhesive hydrogels for tissue-attached sensor

To accurately monitor human physiological activities and promote wound healing, flexible electronics with excellent electromechanical and biotherapeutic properties are demanding. Herein, skin-inspired highly stretchable, tough, and adhesive bilayer composite hydrogels for strain sensing and wound dressing were fabricated through a layer-by-layer polymerization process. Among them, the highly stretchable upper tough layer ensures the composite hydrogel's excellent mechanical and sensing properties, and the lower adhesion layer can be conformal to human skin to enhance sensing sensitivity and stability. Benefiting from the synergistic effect of the bilayer structure, the composite hydrogel presents high stretchability (over 3600%), high toughness (over 200 kPa), and excellent adhesion. In addition, the adhesion layer hydrogel, containing biological macromolecules of tannins and proline, is highly biocompatible to inhibit bacterial growth and promote wound healing. The bilayer composite hydrogel can not only accurately detect human physiological activities as a strain sensor, but also promote rapid wound recovery as wound dressing, showing great potential in health monitoring and wound treatment.