Mechanically‐Compliant Bioelectronic Interfaces through Fatigue‐Resistant Conducting Polymer Hydrogel Coating

Abstract Because of their distinct electrochemical and mechanical properties, conducting polymer hydrogels have been widely exploited as soft, wet, and conducting coatings for conventional metallic electrodes, providing mechanically compliant interfaces and mitigating foreign body responses. However, the long‐term viability of these hydrogel coatings is hindered by concerns regarding fatigue crack propagation and/or delamination caused by repetitive volumetric expansion/shrinkage during long‐term electrical interfacing. This study reports a general yet reliable approach to achieving a fatigue‐resistant conducting polymer hydrogel coating on conventional metallic bioelectrodes by engineering nanocrystalline domains at the interface between the hydrogel and metallic substrates. It demonstrates the efficacy of this robust, biocompatible, and fatigue‐resistant conducting hydrogel coating in cardiac pacing, showcasing its ability to effectively reduce the pacing threshold voltage and enhance the long‐term reliability of electric stimulation. This study findings highlight the potential of its approach as a promising design and fabrication strategy for the next generation of seamless bioelectronic interfaces.