Water‐driven dispersible fiber electrode arrays for position‐dependent intracardiac electrophysiological recording

Abstract Intracardiac electrophysiological recording plays an essential role in identifying abnormal cardiac electrical activity and guiding arrhythmia diagnosis and treatment planning. A key challenge for minimally invasive intracardiac electrodes is to combine reliable transvascular delivery with stable and compliant endocardial contact. Although flexible electrodes improve tissue conformability compared with rigid electrode catheters, their practical use remains limited by the trade‐off between the flexural rigidity required for delivery and the mechanical compliance needed for signal acquisition. Here, we report a water‐driven dispersible fiber electrode (WDFE) array that addresses this trade‐off through hydration‐regulated bundle assembly and separation. Through capillary‐force‐assisted assembly, the WDFE maintains a compact bundled state with relatively high flexural rigidity (2.45 × 10 −4 N·m 2 ), facilitating transvascular delivery. Upon exposure to an aqueous physiological environment, progressive hydration of the sulfobetaine methacrylate‐modified surface weakens interfiber adhesion and enables gradual separation into individual fibers within 5 min. This structural reconfiguration yields separated fibers with markedly reduced flexural rigidity (1.95 × 10 −6 N·m 2 ), enabling compliant interaction with the endocardial surface under flow. Surface chemical characterization, wettability analysis, and modified colloidal‐probe AFM measurements support the stepwise construction of a hydrated, low‐adhesion zwitterionic interface. In electrophysiological recording experiments, the conformal‐contact state of the WDFE showed an approximately 10 dB higher signal‐to‐noise ratio than the floating‐electrode state under the same configuration. The gradient architecture further supported position‐dependent signal acquisition across intracardiac regions. These results suggest that water‐responsive mechanical adaptability provides a feasible strategy for reconciling catheter‐based delivery with compliant intracardiac bioelectronic recording.