Highly Stretchable Self-Adhesive PEDOT:PSS Dry Electrodes for Biopotential Monitoring

Abstract

Wearable dry electrodes are the foundation for the development of long-term, real-time biopotential monitoring devices. However, the physiological signals collected by common electrodes often accompany high noise and motion artifacts due to difficulties in conforming to skin deformations and poor contact between electrodes and skin. In contrast to them, PEDOT:PSS-based dry electrodes become a promising material with adjustable stretchability, conductivity, and adhesion properties to achieve high-quality signal delivery. Herein, we report a highly stretchable self-adhesive film prepared by the conductive polymers PEDOT:PSS, ethylene glycol (EG), poly(vinyl alcohol) (PVA), and d-sorbitol (SOR). In the blending system, SOR will disrupt the dense hydrogen bond interactions within PVA and PSS chains, while PEDOT:PSS/PVA physically cross-linked networks can dissipate strain energy, providing toughness to the films. In addition, the hydroxyl groups on the surface enable the film to be self-adhesive by forming hydrogen bonds with the N and O atoms of the skin stratum corneum. The blended electrode exhibits a conductivity of 200 S/cm and an elongation at break of 120%. Moreover, the electrical properties are still maintained after cyclic stretching (R/R₀ ≈ 1.09). The maximum adhesion force of the film on glass and skin is 1.20 and 0.36 N/cm, respectively. The electrode has good biocompatibility, and its excellent stretchability and adhesiveness are conducive to comply with the skin deformation under different conditions. The contact impedance between dry electrodes and skin is only 77 kΩ cm², which ensures the accurate monitoring of physiological signals including electromyogram (EMG) and electrocardiogram (ECG) during rest or exercise. The signal quality is significantly higher than that of standard Ag/AgCl electrodes. This highly stretchable self-adhesive dry electrode provides a feasible idea for the research of next-generation health monitoring devices.