Recent Advances in Biomimetic Hydrogels for Bioelectronics and Human–Machine Interactions

Biomimetic hydrogels have emerged as versatile bioelectronic interface materials for bioelectronics and human–machine interfaces (HMIs), enabling mechanically compliant and multifunctional interactions between electronic devices and biological tissues. Inspired by the structures and functions of biological systems, these hydrogels incorporate tissue-like mechanics, efficient ionic/electronic transport, robust wet adhesion, and environmental adaptability within hydrated polymer networks, enabling stable bioelectronic interfaces. This review first categorizes biomimetic hydrogels into polymer-based hydrogels, carbon–polymer composites, and metal–polymer composites, with emphasis on their structural features and functional properties. We then discuss biomimetic strategies for regulating charge transport, mechanical performance, and interfacial adhesion through structural and molecular engineering, highlighting how biomimetic principles are translated into material properties. Finally, representative applications in electrophysiological monitoring, biochemical sensing, gesture recognition, and robotic control are discussed to establish the link between biomimetic material design and device functionality. Overall, this review highlights the design principles that connect biological inspiration to material properties and bioelectronic functions, providing a framework for the development of hydrogel-based biointerfaces for advanced bioelectronics and HMIs.