Tongue-inspired gelatin/poly(acrylate-co-acrylamide)-Fe3+ organic hydrogel with tunable mechanical, electrical, and sensory properties

Conductive hydrogels have emerged as one of the most promising candidates for the next generation of wearable soft electronics. However, they face limitations during practical implementation owing to their unbalanced overall properties. In this study, we present a dynamic cross-linked gelatin/poly(acrylic acid-co-acrylamide) (GxPyFez) hydrogel with tunable mechanical strength, self-healing, freezing resistance, electrical conductivity, and high sensitivity, which was prepared by incorporating dynamic Fe3+ ions. The hydrogel was prepared based on the tongue, in which gelatin/poly(acrylic acid-co-acrylamide) and Fe3+ ions mimic the connective tissue and receptor cells of the human tongue. The synergistic effect of reversible crosslinking, along with the modulation of rigid and flexible components enabled tunable flexible structures that exhibit excellent mechanical properties such as elongation at break (569 %) and toughness (8.82 MJ m−3). Notably, the G2P3Fe0.1 hydrogel exhibited remarkable self-healing ability, even at room temperature, while maintaining a good freezing resistance. Furthermore, the G2P3Fe0.1 demonstrated fast response characteristics along with a high sensitivity (GF = 2.75). Consequently, it could be assembled into sensors capable of effectively detecting various movements of the human body; it serves as an electronic skin that responds to diverse external stimuli and monitors underwater motion signals. This study provides new insights into the design of conductive hydrogels with tunable overall properties that can be modified to suit specific application scenarios.