Soft ionic-hydrogel electrodes for electroencephalography signal recording

TLDR: The experimental results demonstrate that the developed soft ionic-hydrogel electrodes can record high-quality EEG signals in a fast and clean way, being a compelling option for EEG-based brain-computer interfaces.

Abstract: Wet gel electrodes have been widely used for electroencephalography (EEG) signal recording, which generally causes skin abrasion and longer preparation time. In this paper, we present soft ionic-hydrogel based electrodes to overcome such drawbacks. In order to conveniently measure the EEG signals, we design the claw-like and patch-like structures for robust connection between metal (Ag/AgCl) electrodes and skin scalps. Next, we experimentally show that the soft ionic-hydrogel based electrodes have similar performance with the conventional wet gel electrodes in terms of the short-circuit noise, electrical impedance, and skin-electrode contact impedance on unprepared human skin, significantly better than dry electrodes and water-based electrodes. We further perform the EEG measurements and steady-state visual evoked potentials (SSVEP) experiments with five subjects to verify the effectiveness of the soft ionic-hydrogel based electrodes. The experimental results demonstrate that our developed soft ionic-hydrogel electrodes can record high-quality EEG signals in a fast and clean way, being a compelling option for EEG-based brain-computer interfaces.