Electronic jelly: Engineering the mechanics of hydrogels for flexible electronics

Abstract Hydrogels—soft, water‐rich polymer networks—are rapidly evolving from traditional biomedical auxiliaries into core functional materials for flexible and biointegrated electronics. However, their practical deployment remains limited by low strength, inadequate toughness, cyclic fatigue, and instability under complex environmental conditions. This review systematically synthesizes mechanics‐oriented design strategies and highlights three major reinforcement routes that have addressed these intrinsic limitations: double‐network architectures, ordered structural motifs, and the regulation of reversible physical interactions. Through these approaches, hydrogels have achieved MPa‐level strength, MJ·m −3 ‐level toughness, and long‐cycle fatigue resistance, enabling reliable operation in stretchable sensors, hydrogel electrolytes, soft actuators, and encapsulation systems. Furthermore, the emerging concept of “intelligent hydrogels” is introduced, wherein physics‐informed constitutive modeling and data‐driven design converge to establish quantitative structure–property–function relationships. Such developments are expected to yield hydrogel systems that combine high water content with enduring mechanical robustness, forming sustainable and biocompatible platforms for next‐generation bioelectronics and soft robotics.