Skin-Conformal Nano-Electrodes for High-Fidelity Electrophysiological Signal Monitoring in Dynamic and Underwater Environments

Wearable electronics with high skin conformability enable a comfortable, skin-like experience and the long-term recording of high-fidelity electrophysiological (EP) signals. However, current research in this field faces challenges, particularly regarding skin adhesion, excessive motion artifacts, and difficulties maintaining signal integrity under various external conditions. Achieving a conformal skin-electrode interface without air voids is crucial for mechanical and electrical stability and to prevent water penetration. In this study, we introduce a nanoscale, skin-conformal electrode designed for continuous, resilient EP signal monitoring with low-motion artifacts and high-water resistance. This flexible electrode combines a hydrophilic MXene conductor and a hydrophobic, ultrathin 300-nm parylene layer, ensuring highly conformal contact even during motion or underwater conditions. The design enhances skin adhesion and reduces skin interfacial impedance, ensuring reliable monitoring of electrocardiogram (ECG) and electromyogram (EMG) signals compared to conventional gel electrodes. As a proof of concept, high-quality ECG signals were successfully recorded, enabling the analysis of heart rate (HR) and heart rate variability (HRV) across diverse, real-world conditions. Simultaneously, we demonstrated stable, long-term signal acquisition of EMG and ECG during treadmill walking, with a focus on detecting tibialis anterior activity during gait cycles. These advancements in nanoscale-ultrathin, skin-conformal electronics pave the way for more resilient, real-time healthcare monitoring, diagnostics, and wearable device applications.