Liquid metal-created macroporous composite hydrogels with self-healing ability and multiple sensations as artificial flexible sensors

Abstract

Hydrogel-based sensors have attracted significant attention owing to their promising applications in artificial intelligence. However, developing robust hydrogel conductors with customizable functionality and excellent sensor properties is challenging. In this study, a new class of sponge-like porous hydrogel conductors integrating self-healing ability, multiple sensations, and excellent mechanical properties is proposed. These attractive comprehensive properties result from liquid metal-created multiple structures. Using acrylic acid as a reactive monomer, liquid metals not only promote the formation of self-healing supramolecular hydrogel networks, but also enable the reduction of graphene oxide to form electronic conductive networks and create macroporous structures in the hydrogel. These structures allow hydrogel conductors to be used as soft sensors with high compressive sensitivity (up to 0.85 kPa⁻¹), a wide range of strain sensitivities (more than 400%), and other multiple sensations such as high sensitivity to temperature evolution, response to solvent change, and sensing atmospheric negative pressure (vacuum). Furthermore, their excellent self-healing ability can further enhance their durability. Such unique multiple sensations are expected to provide novel prospects for the development of sophisticated artificial flexible devices.