A wearable hydrogel-based EEG patch device for human fatigue assessment

Abstract Accurate and quantitative evaluation of human fatigue status is of crucial importance to safe outdoor operations and personal health management. Electroencephalography (EEG) technology offers a non-invasive, rapid and high-accuracy feasible solution, yet it still faces challenges such as large device volume and unstable electrode-skin interface. In this work, we propose a wearable intelligent EEG platform for real-time monitoring and assessment of human fatigue status. A flexible dual-channel (FP1, FP2) EEG patch was fabricated in flexible PET film by coupling screen-printed carbon powder/graphene oxide electrodes with a biocompatible polyacrylic acid/polyvinyl alcohol (PAA/PVA) hydrogel. Among them, the composite carbon structure and the hydrogel provide a low interfacial impedance (98.3 Ω·cm 2 @1 kHz), skin-matched mechanical modulus (3.5 kPa) and a skin-conformal (296 kPa adhesion strength) electronic interface, respectively, laying a solid foundation for acquiring high-quality and stable EEG signals. Furthermore, a smartphone APP was developed to wirelessly operate the EEG platform, as well as to transmit and process real-time EEG data. To verify the effectiveness, a multi-state simulation-induced fatigue test was conducted. The results demonstrate that the proposed EEG platform can detect the EEG spectrum and conduct rhythmic classification processing, in which the θ / β value (>1.5) could serve as a reliable indicator of fatigue, enabling quantitative evaluation and early warning of human fatigue.