Microgel-templated cluster-crosslinked hydrogels for low-hysteresis soft electronics

Conventional conductive hydrogels continue to face challenges in achieving balanced mechanical toughness, low hysteresis, and fatigue resistance. We report a microgel-assisted strategy for fabricating nanocomposite hydrogels with a heterogeneous "sea-island" architecture, where microgel-TMPTMA (MG-T) nanocluster crosslinkers serve as multifunctional crosslinking nodes. The amphiphilic and nanoporous poly(ethyl acrylate-methacrylic acid-divinylbenzene) (PEA-MAA-DVB) microgels function as surfactant-free nanoreservoirs for hydrophobic trimethylolpropane trimethacrylate (TMPTMA), enabling the formation of micrometer-scale rigid "islands" embedded within a soft polyacrylamide (PAAm) "sea" matrix. This unique architecture synergistically combines crack-bridging of MG-T by multi-scale energy dissipation through covalent/hydrophobic interactions, endowing the hydrogel with high-stretchability (1250% strain), high toughness (1201 kJ/m³), exceptionally low hysteresis (<5.0% at 100% strain), and outstanding fatigue resistance. The incorporation of PEDOT:PSS provides long-term stable conductivity and strain-sensitive resistance variations, enabling dual-mode tensile and compressive sensing. As a respiratory sensor integrated into a face mask, it accurately discriminates between normal breathing and coughing events. As a machine learning-enabled electronic skin, it achieves 93.4% recognition accuracy for electromyography signals using a random forest classifier. This work demonstrates a versatile and scalable platform for developing hydrogels that integrate mechanical durability with high-fidelity sensing capabilities, showing great potential for intelligent healthcare monitoring and human-machine interaction systems.