An integrated self-healable and robust conductive hydrogel for dynamically self-adhesive and highly conformable electronic skin

Abstract

Mimicking the mechanical and sensory properties of human skin to develop a highly conformable electronic skin integrated with robust, self-healable, and ultra-sensitive properties is promising but still a great challenge. In this work, we report a novel dynamic self-adhesive and self-healable conductive hydrogel material that is applicable to highly conformal and ultrasensitive electronic skin devices. In the obtained gel system, the incorporated tannic acid coated cellulose nanocrystals (TA@CNCs) act as dynamic reinforcing bridges in the dual cross-linked gel network that are mediated by reversible hydrogen bonds and electrostatic interactions, allowing a unique combination of superior mechanical performance (strain >700%) and reliable autonomous self-healing capability (HE >90%). The formation of conductive polyaniline (PANI) network in the obtained TC-Gel leads to both high conductivity (0.13 S cm⁻¹) and high sensitivity (GF = 11.2), which are advantageous for the real-time detection of large human motions, tiny muscle movements, and physiological signals. Notably, the TC-Gel exhibits the dynamic self-adhesive performance that integrates both strong adhesion (∼440 N m⁻¹) and easy detachment in water for 3 min. As a proof of concept, we demonstrate that this unique self-adhesive strategy is able to increase interface interlocking and conformal contact between the TC-Gel based sensor and dynamic biological surface, contributing to the high sensory performance with a low noise level and negligible baseline fluctuation. We envisage that this work broadens the avenue for designing multifunctional cellulosic-based hydrogels to promote the application of integrated electronic skin with high sensory properties and comfortable user experiences.