Soft, flexible, and stretchable materials with exceptional toughness and adhesion properties hold great potential for robust strain sensor development across various applications. An ion-conductive hydrogel, consisting of polyacrylamide (PAM) and 2-hydroxyethyl acrylate (HEA), LiCl incorporates via imidazole-based metal-organic framework (MOF) nanoparticles to introduce multifunctionality and enhance mechanical properties, including stretchability, toughness, energy dissipation, and hysteresis loop, for use as wearable strain sensors. The zeolite imidazolate frameworks-8 (ZIF-8) reinforced nanocomposite hydrogels exhibit high fracture elongation up to 800%, fracture strength up to 110 kPa, fracture toughness up to 0.45 MJm-3, and minimal hysteresis as low as 2.6%. Additionally, the hydrogels adhere well to various surfaces, including steel, glass, silicone rubbers, aluminum, and nitrile rubbers, and demonstrate resilience in freezing temperatures down to -20°C. The synergy of electrostatic interactions between the AM-HEA polymer chain and nanoporous ZIF-8 enhances the mechanical properties, while the abundant hydrogen bonds originating from the polarized surface of ZIF-8 also introduce multifunctionality to the nanocomposite hydrogel. These properties enable the hydrogels to act as strain sensors with a high sensitivity gauge factor of ~3.00, along with fast response and recovery times of 280 ms and 330 ms respectively. The versatile multifunctionality of the ZIF-8 reinforced nanocomposite ionic hydrogels prepared herein could offer a novel approach to designing and fabricating advanced all-round strain sensors for promising applications in biomedical fields, particularly in health assessment and human motion monitoring.
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