Biodegradable and flexible electronic skin

The conductive flexible electronics with the conductive and flexible characteristics are widely used in the wearable devices, electronic skin (E–skin), flexible sensor etc., which combine the functionality of traditional electronics with the flexibility of materials. In this study, a double–network hydrogel fabrication method was proposed based on the ion–conjugate complementary conduction, and the temporary ion bridging conjugated conductive lines were achieved by the stability of flexible electrons and high conductivity of conjugated conductivity. The obtained flexible hydrogel with the double–network is composed of sodium alginate (SA)–hydrogel and reduced graphene oxide (rGO), where the ionic and second conjugated conductive networks are caused by the Ca 2+ –SA and rGO–SA, respectively. The addition of rGO significantly enhances the mechanical robustness and interfacial adhesion force of the hydrogels, and the fracture strain is increased from ∼40 % to ∼80 % and the adhesion force is improved from 0.06 N to 0.08 N, demonstrating its suitability for the flexible and wearable electronic applications. Moreover, the resistance of rGO–SA–hydrogels decreased by 65.1 % compared with the Ca 2+ –SA-hydrogels, which corresponds to the increase of conductivity.