A stretchable, permeable, and biocompatible fiber-reinforced hybrid hydrogel electrode for highly stable electrophysiological signal recording†

Abstract

The synergistic optimization of mechanical strength, skin-like elastic modulus, electrode-skin impedance, permeability, and biocompatibility remains a critical challenge in the deployment of flexible electrodes as a central component of noninvasive electrophysiological signal recording. Here, we propose a fiber-reinforced hybrid hydrogel (FRHH) electrode that integrates the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and titanium carbide (Ti₃C₂T_x) with the mechanical resilience of styrene–ethylene–butylene–styrene (SEBS) fibers within a PVA hydrogel matrix. The FRHH electrode demonstrates remarkable stretchability, with a tensile strain reaching up to 1485%, coupled with moderate tackiness. It also shows low impedance at a frequency of 1000 Hz at the electrode-skin interface (2829.3 Ω), which is significantly lower than the impedance of commercial wet electrodes (6654.5 Ω) and dry electrodes (17 611.2 Ω). Furthermore, the FRHH electrode showed excellent biocompatibility in preliminary in vivo tests, allowing for continuous on-skin application for up to 12 hours without causing inflammation or allergic reaction. The electrode maintains conductivity and signal integrity under significant deformation, making it suitable for continuous and stable recording of electrocardiogram (ECG) and electromyogram (EMG) signals, even during physical activity. Additionally, the FRHH electrode shows promise in EMG-based gesture recognition and can recognize precise muscle activation patterns. The FRHH electrode holds promise for a wide range of applications, including continuous health monitoring, athletic performance tracking, and medical diagnostics, and could significantly contribute to advances in noninvasive and wearable healthcare technologies.