Viscoelastic Adhesive,\nSuper-Conformable, and Semi-Flowable\nLiquid Metal Eutectogels for High-Fidelity Electrophysiological Monitoring

Abstract

Integrating gels with human skin through wearables provides\nunprecedented\nopportunities for health monitoring technology and artificial intelligence.\nHowever, most conductive hydrogels, organogels, and ionogels lack\nessential environmental stability, biocompatibility, and adhesion\nfor reliable epidermal sensing. In this study, we have developed a\nliquid metal eutectogel simultaneously possessing superior viscoelasticity,\nsemiflowability, and mechanical rigidity for low interfacial skin\nimpedance, high skin adhesion, and durability. Liquid metal particles\n(LMPs) are employed to generate free radicals and gallium ions to\naccelerate the polymerization of acrylic acid monomers in a deep eutectic\nsolvent (DES), obtaining highly viscoelastic polymer networks via\nphysical cross-linking. In particular, graphene oxide (GO) is utilized\nto encapsulate the LMPs through a sonication-assisted electrostatic\nassembly to stabilize the LMPs in DES, which also enhances the mechanical\ntoughness and regulates the rheological properties of the eutectogels.\nOur optimized semi-flowable eutectogel exhibits viscous fluid behavior\nat low shear rates, facilitating a highly conformable interface with\nhairy skin. Simultaneously, it demonstrates viscoelastic behavior\nat high shear rates, allowing for easy peel-off. These distinctive\nattributes enable the successful applications of on-skin adhesive\nstrain sensing and high-fidelity human electrophysiological (EP) monitoring,\nshowcasing the versatility of these ionically conductive liquid metal\neutectogels in advanced personal health monitoring.