Highly Adhesive, Ultrafast Self-Healing, and Conductive Dopamine-Based Polymer Hydrogels for Sensitive Human Motion Sensing

The use of hydrogel strain sensors in flexible electronic wearable devices has garnered significant attention. However, achieving hydrogels with comprehensive properties such as excellent tensile strength, strong adhesion, rapid self-healing, and high sensitivity simultaneously remains challenging. Herein, inspired by mussels, we developed a straightforward polymerization process in an aqueous solution using the polymerizable monomer 3-methylacryloyldopamine, containing the catechol structural unit, along with acrylic acid, sodium acrylate, ethylene imine polymer, and the zwitterionic monomer [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl). This resulted in a hydrogel with a double-network structure featuring multiple dynamic interactions. The hydrogel sensor exhibited remarkable tensile properties (up to 4200%), strong adhesion (adhesion for wood: 3370 kPa), rapid self-healing ability (3 s), and high sensitivity (GF = 13.75), allowing for accurate and repeatable detection of both large-scale and subtle human movements. Furthermore, the addition of glycerol endowed the hydrogel with the capability of functioning at low temperatures (-40 degrees C). Such adhesive and self-healing dopamine-based hydrogel also has potential in electronic skins, hydrogel dressing, and human-machine interface.