3D‐Printed Mixed Ionic‐Electronic Conductive Polymer Composites for Long‐Term Bioelectronic Sensing

Abstract Reliable, long‐term monitoring of health data is becoming increasingly essential in modern healthcare. While computational and machine learning capabilities continue to advance, the lack of lightweight, conformable, and customizable hardware remains a key limitation. In the context of heart health, traditional electrocardiogram (ECG) electrodes are rigid and often uncomfortable for continuous wear. Existing soft electrodes tend to be either cost‐prohibitive or unreliable over extended use. In this work, all‐polymer, 3D‐printed, highly stable, and conformable ECG patches are developed for long‐term signal acquisition. Through material optimization, composite materials with electrical conductivity up to 1.7 S cm ⁻¹ are developed, maintaining over 85% of their conductivity after 60 days of exposure to open air. These materials also exhibit remarkable stretchability (strain at break up to 253%) and high mechanical strength (tensile strength of 25 MPa). The formulated inks are fully compatible with 3D material extrusion techniques, significantly reducing manufacturing costs. The printed electrodes are flexible, stretchable, and capable of recording high‐quality ECG signals, performing comparably to state‐of‐the‐art metal electrodes, even after more than a month of use‐and‐store in open air.