Cost‐Effective Ultrathin SEBS‐Ag Electrodes of Substrate‐Regulated Microcracks for Robust Skin Electrophysiology

Ultrathin wearable interfaces are essential for continuous, long-term electrocardiogram (ECG) monitoring. However, their widespread deployment is limited by the high economic and environmental costs of gold-based conductors and the single-use nature of ultrathin devices. To address these challenges, a cost-effective, silver-based ultrathin stretchable electrode is developed by systematically tuning the mechanical stiffness and chemical polarity of polymeric substrates. Through a deep investigation into the silver embedment mechanism and crack evolution dynamics under stretch, we established the critical structure-property relationships governing electromechanical performance. This yielded an optimized ultrathin stretchable electrode (7.6 µm) with a skin-mimetic modulus (1.35 ± 0.03 MPa), low sheet resistance (9.26 Ω/sq), and robust cyclic stability (resistance change of ∼1.7 after 5000 cycles). The resulting device achieves conformal skin contact, enabling low-artifact ECG monitoring over 24 h. Furthermore, integrating a robust adhesive ion-gel interface allows the electrode to effectively suppress motion artefacts during vigorous physical activity. It sustains a high signal-to-noise ratio (SNR) of 29.27 ± 1.24 dB during 13 km/h running, significantly outperforming commercial Ag/AgCl electrodes that exhibit severe motion artifacts. This strategy, merging cost-effective manufacturing with superior dynamic signal fidelity, provides a scalable and practical paradigm for ubiquitous low-cost health monitoring systems.