Cholinium-based eutectogel electrode for high-quality dynamic EEG/ECG monitoring exceeding 48 hours

Abstract Bioelectrical signals, especially electroencephalography (EEG) and electrocardiography (ECG), are indispensable for health assessment. However, achieving high-quality signal acquisition while ensuring long-term stability remains a significant challenge in the bioelectrical electrodes. Herein, a cholinium-based eutectogel (ChCl-egel) is reported for dynamic ECG and EEG monitoring. By utilizing hydrogen bonding of deep eutectic solvents (DESs) to modulate conductivity, the ChCl-egel realizes an ultra-low skin impedance (4.7 kΩ at 10 Hz) with reliable stability. Additionally, the ChCl-egel exhibits excellent conformal contact and biocompatibility. During ECG monitoring, the ChCl-egel offers an 8 dB improvement in signal-to-noise ratio (SNR) compared to commercial ECG electrodes (3 M, Red Dot) over 48-hour period, enabling dynamic record under high-intensity exercises. In an 18-hour steady-state visual evoked potential (SSVEP) experiment, it can match the scalp impedance of commercial gel and support longer record. With high-quality dynamic monitoring capability, the ChCl-egel provides a promising solution for long-term bioelectrical signal acquisition.