Lignosulfonate-Derived Conducting Organohydrogel as Anisotrpic Bioadhesive for Motion-Artifact-Free Epidermal Bioelectronics

Gel-based adhesives show promising prospects in epidermal bioelectronics because of their potential applications in physiological signal collection and electrical stimulation. An ideal epidermal adhesive should exhibit robust adhesion for lamination and poor adhesion for easy peeling, in addition to strain-insensitivity in electrical properties for motion-artifact-free physiological signal collection. Here, lignosulfonate-derived organohydrogel adhesives with anisotropic and tunable adhesion, together with unprecedented strain-insensitivity are synthesized. The organohydrogel exhibits a high interfacial toughness of 728 J m −2 on fresh porcine skin, while the adhesion can be screened by covering a denatured silk fibroin. An anisotropic adhesive with an adhesion heterogeneity is designed, showing a 14.2-fold difference in adhesion strength along two different directions for on-demand attachment and removal. The adhesive can transform into a highly porous structure, which has only a 3% resistance increase at 100% strain. The strain-insensitivity of the adhesive lies in the strong interaction of ions and the 3D porous structure, which enables motion-artifact-free and high-quality electrophysiological signal collection within the strain range of the human skin. The lignosulfonate-derived on-demand organohydrogel adhesive is expected to be used in epidermal bioelectronics, human-machine interaction, metaverse, and beyond.