This review has examined recent advancements in hydrogel-based soft bioelectronics for personalized healthcare, focusing on three key challenges: achieving wide-range modulus coverage, balancing multiple functional properties and achieving effective organ fixation. We explored strategies for tuning hydrogel mechanical properties to match diverse tissues, from soft brain to stiff tendons, through innovative network designs. Methods for imparting conductivity to hydrogels, including ionic conductivity, conductive fillers, and conductive polymers, were analyzed for their unique advantages in bioelectronic applications. We highlighted approaches for decoupling mechanical and electrical properties in hydrogels, such as network design strategies incorporating sliding-ring structures to address the brittleness of conductive polymers, and the novel concept of all-hydrogel devices to fundamentally decouple mechanical and electrical performances. These innovations provide potential solutions to the traditional trade-offs between mechanical robustness and electrical conductivity. Beyond electrical interfacing, we discussed hydrogels' potential in acoustic and optical coupling, expanding their functionality in bioelectronics. The review introduced hydrogel self-morphing as an alternative to adhesion-based methods for targeted organ fixation, offering improved conformability and reduced tissue damage. Finally, we categorized and analyzed applications of hydrogel-based bioelectronics in wearable and implantable devices, demonstrating their versatility in personalized healthcare, from epidermal sensing and therapy to neural interfaces and bioadhesives.
