Tailored construction and functional applications of conductive hydrogels for bioelectronic interfaces

Conductive hydrogels have emerged as core foundational materials for bioelectronic interfaces, uniquely bridging the mechanical and electrical property gap between biological tissues and electronic devices. Unlike previous reviews that primarily focus on material classification and broad device applications, this review adopts an interface-centric perspective, specifically targeting the performance optimization of conductive hydrogels for bioelectronic interface applications. We first categorize conductive hydrogels according to their underlying conductive mechanisms, and describe the morphology and interfacial interactions of conductive nanomaterials with different dimensionalities. We then systematically examine interface-relevant design strategies: (i) achieving conformal contact by reducing stiffness, enhancing adhesion, and decreasing thickness; (ii) constructing a reliable and stable interface by improving toughness and imparting self-healing properties; and (iii) enhancing signal transmission efficiency through the synergistic combination of high conductivity, efficient charge transfer, and low interfacial impedance. We further review recent advances in flexible bioelectronic devices, and finally discuss current challenges and future directions, including clinical translation, device miniaturization, and integration into fully automated bioelectronic systems.