A Photocurable Conductive Hydrogel with Synergistic Electron and Ion Transport for Long-Term, High-Fidelity Electroencephalography Acquisition

Abstract

Long-term, high-fidelity electroencephalography acquisition requires bioelectronic interfaces that simultaneously exhibit low skin–electrode impedance, stable electrical conductivity, mechanical compliance, and environmental stability. However, most conductive hydrogels suffer from progressive water loss, disruption of conductive pathways, and increasing interfacial impedance during prolonged use, resulting in signal degradation and limiting their application in wearable brain–computer interfaces. This paper reports a conductive hydrogel based on photocurable gelatin methacryloyl (GelMA), which integrates a covalently cross-linked GelMA network, an MXene electronic conductive network, an NaCl-mediated ion transport network, and a glycerol–water hydrogen bond network, thereby establishing a synergistic electronic–ionic conductive interface with enhanced water retention and long-term stability. The rationally engineered multiscale network simultaneously improves mechanical robustness, electrical conductivity, and interfacial conformity while effectively suppressing conductivity decay induced by dehydration. The optimized hydrogel exhibits a compressive strength of 680.1 kPa, an electrical conductivity of 0.304 S m^–1 (10 Hz), a low skin–electrode impedance of 6.501 kΩ, and retains 88.35% of its initial water content after 72 h under ambient conditions. Benefiting from the synergistic electron–ion transport mechanism and stable hydrated interface, the hydrogel electrode enables reliable acquisition of resting-state EEG and steady-state visual evoked potential signals, achieving a signal-to-noise ratio of 15.05 dB and maintaining stable electrophysiological performance after 12 h of continuous wear. This work demonstrates a general strategy for constructing long-term stable bioelectronic interfaces through the synergistic regulation of mechanical networks, electron transport, ion migration, and water retention, providing a promising platform for next-generation wearable EEG electrodes and continuous brain–computer interface applications.