Adaptive topological networks enabled by high-aspect-ratio cellulose nanofibrils for robust and self-healing hydrogel wearable sensors.

Flexible wearable sensors for personalized healthcare and human-machine interaction require substrates combining high mechanical strength, rapid self-healing, and stable electro-conductivity. However, existing materials suffer from intrinsic trade-offs among these properties. Inspired by biological networks, we introduce a conceptual paradigm of adaptive topological networks (ATN) enabled by high-aspect-ratio cellulose nanofibrils (HAR-CNF, ~230). Unlike conventional fillers, our ATN framework positions HAR-CNF as a topological "entropy modulator" and "mechano-chemical coupling agent" orchestrating the interplay among three networks: a HAR-CNF physical entanglement network, a borate ester dynamic covalent network, and a silver nanowires (AgNWs) percolation network. This architecture resolves the trade-offs through three synergistic mechanisms-topological entropy modulation for energy dissipation, force-assisted dynamic bond reassembly for ultra-fast healing (99.5% efficiency, 2 min), and hierarchical confinement with a slip-lock mechanism for ultra-wide-range sensing (0-1000% strain). The hydrogel achieves a tensile strength of 238 kPa and an elongation at break of 1600%. The assembled sensor exhibits high sensitivity (gauge factor = 6.74, pressure sensitivity = 0.583 kPa-1), rapid response (179 ms), and stable cycling over 1000 s, enabling monitoring of facial micro-expressions, joint motions, and spatial pressure mapping via a 5 × 5 sensing array. This ATN paradigm offers a transformative platform for high-reliability flexible electronic skins.