Antifouling All‐Polymeric Microneedle Array for Long‐Term Wearable ECG Monitoring

Cardiovascular disease demands reliable long‐term monitoring for early and accurate diagnosis. While conventional gel electrodes are commonly utilized for monitoring electrocardiogram (ECG) signals, they have limitations, such as dehydration‐induced signal degradation and motion artifacts, hindering their effectiveness for continuous long‐term use. To address these issues, this study develops a biocompatible and all‐polymeric microneedle electrode (MNE) optimized for stable ECG monitoring over extended periods. The MNE surface is sequentially coated with poly(3,4‐ethylenedioxythiophene):tosylate (PEDOT:Tos) to reduce the interfacial impedance (0.63 kΩ∙cm 2 at 10 Hz), followed by zwitterionic sulfobetaine methacrylate (SBMA) to prevent nonspecific protein adsorption and cellular adhesion (84.2% and 98.6% reduction in E. coli and BSA, respectively). Moreover, the SBMA‐coated MNE demonstrates excellent mechanical strength, allowing it to penetrate human skin without deformation, as verified by optical coherence tomography and insertion‐force assessments. In practical applications using a wireless wearable ECG monitoring system, the SBMA‐coated MNE consistently captures high‐quality ECG signals over a 14‐day period, significantly outperforming gel electrodes under dynamic movement conditions.