Tendon-Inspired, Fatigue-Resistant Conductive Organohydrogels via Solvent-Exchange-Assisted Mechanical Training

The hierarchical fiber architecture of tendons, which integrates high fatigue resistance, high water content, and rapid responsiveness to stimuli over millions of annual cycles, makes them an ideal model for long-term wearable intelligent materials. However, synthetic hydrogels prepared via methods such as electrospinning, freeze-thawing, freeze-casting, and solvent exchange, often lack comprehensive structural and functional integration compared to their biological counterparts. To address this challenge, we developed a synergistic fabrication strategy that integrates freeze-thawing, mechanical training, and solvent exchange to construct hierarchically structured hydrogels. The polyvinyl alcohol-based hydrogel that has been repeatedly freeze-thawed, was then immersed in a glycerol/water solvent containing ferric chloride and subjected to approximately 200 000 mechanical training cycles. The resulting hydrogel exhibited remarkable comprehensive properties, including a tensile strength of 9.38 MPa, a fracture energy of 187.5 kJ m^-2, a fatigue threshold of 7850 J m^-2, a conductivity of 0.64 S m^-1, and excellent flexibility even at -80°C. Leveraging this multifunctionality, the hydrogel was further assembled into a strain sensor capable of precise, rapid monitoring of finger motion and was employed in a gesture-controlled drone system. This work provides a universal and effective approach to designing fatigue-resistant hydrogels, offering new insights into the development of next-generation bioinspired, flexible electronic materials.