A self-healing, long-lasting adhesive, lignin-based polyvinyl alcohol organo-hydrogel for strain-sensing applications

Abstract

Hydrogel-based flexible sensors have garnered considerable interest in the fields of soft electronics, robotics, and human-machine interfaces. For better practical applications, integrating multiple properties—such as self-adhesive, anti-freeze, anti-volatile, self-healing, and antibacterial—into a single gel for flexible sensors remains a challenge. In this paper, a multifunctional lignin-based polyvinyl alcohol gel, containing dynamic covalent bonds, hydrogen bonds, and coordination bonds, is constructed by a simple one-pot method, in which ethylene glycol/water chosen as a binary solvent and KI as a conductive medium. The resulting organogel exhibits self-healing, long-lasting adhesion, UV shielding, antibacterial properties, excellent frost resistance (−20 °C), and volatile resistance properties. In addition, the organogel-based sensor demonstrates satisfactory sensitivity in detecting joint movements and facial expressions. This study provides a new strategy for developing a versatile flexible sensor through the introduction of renewable and bio-based lignin, promising applications in the fields of wearable electronics.