A novel passive electrode based on porous Ti for EEG recording

In this paper, we present a novel passive electrode based on porous titanium (Ti) for electroencephalography (EEG) recording. There was a reservoir with a capacity of 200 μl on the passive electrode. When the slight pressure was applied on the reservoir, the electrolyte in the reservoir permeated from micro-holes of the porous Ti onto the skin. The liquid could provide continuous wet interface between electrode and skin to maintain low and stable contact impedance. After the pressure was removed, the liquid withdrew into the reservoir to make the skin keep clean. Meanwhile, the amount of the permeated liquid was too little to form short circuit of adjacent electrodes. We used physiological saline as the electrolyte because it was not different from conductive gel of the conventional silver/silver chloride (Ag/AgCl) electrode and didn't cause skin irritations or allergic reactions. The testing results indicated that the passive electrode had a relatively low skin-electrode contact impedance. The alpha rhythm and N100 auditory evoked potential were measured to evaluate the electrode performance for EEG recording.