Pin-Shaped Ag/AgCl Fabric Electrode Coated With Hydrogel for EEG Recording in Hairy Areas

In this article, a pin-shaped fabric electrode is designed to achieve low contact impedance in hairy area and record electroencephalogram (EEG) signals. By covering the Ag/AgCl-coated conductive fabric on the surface of the polyurethane (PU) columns, it can form pin-shaped electrode and directly contact the scalp through the hair. To further reduce the contact impedance, the fabric is filled with hydrogel with moisturizing properties. This electrode combines the advantages of pin-shaped dry electrode and planiform fabric electrode. The skin-electrode contact impedance of the fabric electrode is usually about 10.9± 2.7 kΩ , which is much lower than dry pin-shaped electrode and lower than most hydrogel or semi-dry electrodes that require a separate electrolyte injection. The hydrogel filled in the fabric structure is protected by the fabric structure and will not be easily worn during use. The amount of hydrogel is very small and the surface of the electrode is basically dry. The fabric electrode can be used and stored like normal pin-shaped dry electrode. The average contact impedance kept below 15 kΩ after 30 days. The fabric electrode has a root-mean-square (rms) noise of 0.3214μ V, which means its EEG signal quality can be similar to wet electrode.