headband channels show 'railed' after long session
hansamali_paul
Sril Lnkan
I have purchased and used EEG headband kit with Cyton board to collect EEG signals few months ago. at first i could collect them properly, but now when I try to collect signal for a long period of time the channels get railed and could not make them not railed. what will be the problem. i have replaced snap electrodes and wires too, but the problem remains.
Comments
Paul, hi.
The dry electrodes used in the kit are very sensitive to the amount of pressure applied on the skin by the band. Have you tried tightening the band somewhat? You don't want to make it uncomfortable to wear.
If you look at the tips of the comb electrodes, do the look as black/grey as the rest of the electrode body? If the tips are worn, this can reduce effectiveness. Similarly check the inner surface of the ear clips. The electrodes are plastic base, plated with silver, then chlorided. If you see silver showing through, it means the chloride coating has worn off.
It's a good idea to have a clean / shampooed head, but avoid any conditioners, those 'after wash' products can create a layer that interferes with recording. With the ear clips sometimes better conductivity can result if the ear lobes are moistened with water slightly.
William