Sinusoidal stretchable fibrous electrodes regulate cardiac contraction

•The introduction of controllable sinusoidal structures by speed programming in MEW.•The sinusoidal electrode exhibits electrical properties similar to the human myocardium.•The anisotropic design endows the electrode with biomimetic mechanical anisotropy.•The stretchable electrode successfully paced the HL-1 cardiomyocytes at 1 and 2 Hz.•The fibrous sinusoidal structure conforms to the mechanically dynamic beating heart. The flexible electronics allowing regulate the performance of engineered cardiac tissue represents a promising approach for the treatment of cardiac diseases. However, the conventional electronic system is usually limited by mismatched biomechanical properties. Herein, exploring the natural flow behavior of the polymer melt in Melt electrowriting (MEW) under its non-linear printing phase, a fibrous mesh electrode with a sinusoidal anisotropic structure resembling the collagen fiber architecture in the heart was straightforwardly created. The structure-defined, biomimetic anisotropic viscoelastic behavior, withstanding thousands of cyclical and constant stretching, together with the fine-tuned anisotropic electrical properties, were employed at the electrode-cell interface for synchronizing cardiomyocytes beating. The anisotropic fibrous mesh electrode, which is 100 times thinner than human hair, easily conforms to the heart’s anisotropic structure to introduce bioelectrical stimulation to the surface of the diseased tissue evenly across a wide area. Electrical stimulation through the electrodes could modulate HL-1 murine cardiomyocyte contraction frequency. Meanwhile, human iPSC derived cardiomyocytes (iPSC-CMs) with well-developed sarcomeres and cellular electrical coupling were aligned and elongated along the stretchable electrode, which accommodated their in-plane contractions along the short axis, suggesting the good mechanical conformability to the heart beating. The stretchable electrode demonstrated in vivo biocompatibility by histology analysis. Overall, our anisotropic, stretchable electrode mesh holds great potential for cardiac repair.