An orange peel-based hydrogel composite for touch-responsive electronic skin

As global environmental issues increase, sustainable use, disposal, and production of materials play an important role. The world produces 1.3 billion tons of food waste annually, of which about 15% are edible fruit peels. Here, we use freeze-dried orange peels as the main material in a hydrogel to prepare a flexible, natural, biocompatible, and sustainably produced electronic skin. We introduce the lyophilized mesocarp of orange and a copper-based metal-organic framework into a polyvinyl alcohol/hyaluronic acid matrix hydrogel, which can occur under mild conditions. The design allows the polymers to connect through intermolecular interactions rather than covalent bonding, which improves the material's mechanical properties while retaining the self-healing ability. The orange peel-based hydrogel exhibits high elongation at break (290%), enhanced tensile stress, self-healing, conductivity (0.14 S/m), and antibacterial properties (95.3%). These results demonstrate an option for environmentally friendly materials for electronic skin.