Lignin-Stabilized Tough, Sticky, and Recyclable Liquid Metal/Protein Organogels for Multifunctional Epidermal Smart...

Biomass-encapsulated liquid metals (LMs) composite gels have aroused tremendous attention as epidermal smart materials due to their biocompatibility and sustainability. However, they can still not simultaneously possess toughness, adhesion, and recoverability. In this work, the tough, sticky, and recyclable protein-encapsulated LMs organogels (GLM_x) are fabricated through the micro-interfacial stabilization of LMs by lignin and the following preparation of food-making inspired gels. With the help of lignin modification, the LMs micro-drops demonstrated uniform dispersion in the protein matrix, as well as dense non-covalent interactions (e.g., H─bond and hydrophobic interaction) with amino acid residues in peptide chains, which endowed the GLM_x with high conductivity (≈5.4 S m^-1), toughness (≈738.2 kJ m^-3), self-adhesiveness (a maximal lap-shear strength of ≈58.3 kPa), and recoverability. By tightly adhering onto human skin, the GLM_x can act as epidermal sensors to detect drastic (e.g., joint bending) and subtle body movements (e.g., swallowing) and even recognize handwriting and speaking in real-time. Moreover, the organogels can also harvest solar energy and convert it into heat and electricity, which is promising in self-powered intelligent devices. Thus, this work paves a facile way to prepare protein/LMs composite organogels that are suitable for multiple applications like healthcare, human-robot interactions, and solar energy conversion.