  Bioelectronic implants with soft mechanics, biocompatibility, and excellent
electrical performance enable biomedical implants to record
electrophysiological signals and execute interventions within internal organs,
promising to revolutionize the diagnosing, monitoring, and treatment of various
pathological conditions. However, challenges remain in improving excessive
impedance at the bioelectronic-tissue interface and thus the efficacy of
electrophysiological signaling and intervention. Here, we devise orbit symmetry
breaking in MXene (a low-cost scalability, biocompatible, and conductive 2D
layered material, that we refer to as OBXene), that exhibits low
bioelectronic-tissue impedance, originating from the out-of-plane charge
transfer. Furthermore, the Schottky-induced piezoelectricity stemming from the
asymmetric orbital configuration of OBXene facilitates interlayered charge
transport in the device. In this study, we report an OBXene-based cardiac patch
applied on the left ventricular epicardium of both rodent and porcine models to
enable spatiotemporal epicardium mapping and pacing, while coupling the
wireless and battery-free operation for long-term real-time recording and
closed-loop stimulation.
