Reverse-curve-arch-shaped dry EEG electrode for increased skin–electrode contact area on hairy scalps

Electroencephalography (EEG) is electrical brain activity that can be measured on the scalp with Ag/AgCl electrodes and conductive gel. However, time-consuming preparation procedures, dehydration of the gel, and skin irritation are crucial drawbacks of using such electrodes. Alternative approaches involving the use of spiky dry electrodes have their own drawbacks such as limited skin-electrode contact area, high skin-electrode impedance, and pain. Reverse-curve-arch-shaped dry EEG electrodes for use in increasing the skin-electrode contact area on hairy scalps are presented. The proposed electrode was fabricated from sterling silver using a three-dimensional printer. To increase the contact area between the skin and an electrode, an electrode was designed to have reverse-curve arches which were arranged in a row on the electrode base. The curvature of the arches was designed to match the curvature of the scalp to maximise the contact area and disperse the pressing force. To validate the proposed electrode design, comparison experiments for EEG and skin-electrode contact impedance were conducted, and the proposed electrode was found to perform better than a commercially available finger-type dry electrode.