Bioinspired 3D printed elastomer-hydrogel hybrid with robust interfacial bonding for flexible ionotronics

[Display omitted] •A hybrid is prepared with a hydrogel matrix and a 3D-printed elastomeric skeleton.•The hybrid material combines high mechanical properties and ionic conductivity.•Robust interface is created by forming strong covalent bonds at the interface.•The hybrid material exhibits remarkable self-healing capability.•The hybrid demonstrates high sensitivity and reliability as flexible sensors. Hydrogels are widely used in flexible ionotronics due to their continuous conductive phase and good biocompatibility. However, their poor mechanical properties affect their stability and lifespan. It is a significant challenge to prepare hydrogels with both high conductivity and mechanical strength, as improving the mechanical properties often results in a tighter network, which reduces electrical conductivity. Human skin is composed of a stiff collagen fibril scaffold for resisting external damage, and a soft matrix that detect various stimuli through ion transport. Herein, inspired by the structure of human skin, a hydrogel composite with remarkable mechanical properties, high ionic conductivity, and self-healing property is prepared. The composite structure with 3D printed elastomeric skeleton and hydrogel matrix, addresses both the contradiction between the ionic conductivity and mechanical properties of hydrogels, as well as the difficulty of realizing complex macrostructures of the skeleton. The issue of weak interface in composites is resolved by creating interfacial covalent bonds. The composite’s self-healing property, combined with a robust interface, ensure the stability and longevity of the composite when used as flexible sensors. This novel approach of creating robust interface is also employed in the encapsulation of hydrogels and the fabrication of flexible microcircuits.