High-Strength, Low-Hysteresis Hydrogel Fibers via Coordination-Locked Entangled Networks for Wearable Sensors

Hydrogel fibers (HFs) have emerged as a promising platform for wearable sensing, owing to their large length-todiameter ratio, fabric compatibility, and modular architecture. However, the high hysteresis resulting from energy dissipation during deformation remains a critical barrier to reliable sensing. Moreover, integrating low hysteresis with high strength via a simple fabrication process poses a further significant challenge. In this study, poly(acrylamide-co-itaconic acid) HFs were successfully prepared by constructing a highly entangled network locked through zirconium ion coordination. The resilience and strength of HFs were decoupled by the designed structure, thereby achieving unique mechanical properties characterized by low mechanical hysteresis (11% for 200% strain), high strength (1.1 MPa), improved toughness (2.58 MJ/m³) and moderate modulus (326 kPa). Furthermore, this coordination-locked entangled network strategy demonstrated broad applicability for selected aliphatic vinyl monomers with carboxylic acid, yielding HFs with high strength and low hysteresis. The obtained HFs-based strain sensor exhibited a stable and linear response (1%-200% strain), with a low electrical hysteresis (1.15%), a high gauge factor (1.01), a rapid response/recovery time (< 40 ms), and stretching rate adaptability. The sensor enabled real-time motion/breathing monitoring and emergency Morse code communication for speech-impaired users, demonstrating the promising application of these HFs in wearable sensing.