Facile and robust integration of functional hydrogels into micropillar-structured elastomer platforms for stable cardiac bioelectronics.

Establishing stable electrical communication between living tissues and bioelectronic devices requires soft, conductive, and conformable interfaces. Conductive hydrogels are attractive for this role because their hydrated polymer networks and mixed ionic/electronic conductivity reduce impedance and enhance charge transfer. Yet, challenges remain in integrating hydrogels with device components and achieving reliable tissue adhesion. Here, we present a materials and structural design strategy that enables electrically and mechanically robust devices through sequential formation of elastomer-metal-hydrogel multilayers and single-step laser patterning. The device consists of a micropillar-structured waterborne polyurethane substrate with a Au layer strongly bonded to the pillars, showing <2% resistance change under 28% strain. Functional hydrogels provide low interfacial impedance (~36.2 ohms at 1 kilohertz), effective insulation (~51,536 ohms at 1 kilohertz), and strong adhesion (~226 newtons per meter on cardiac tissue). Without elastomer-hydrogel decoupling, performance remains stable under dynamic aqueous conditions. Applied to rodent cardiac tissue, the integrated interface enables real-time electrocardiography monitoring and feedback-controlled electrical stimulation.