Ultracortex, managing longer hair
Hello,
we are having some trouble getting the correct impedance levels in those with long hair and was wondering if anyone has any tips for getting good readings when they have longer or thicker hair. We also tried using the 5 mm Comb Reusable Dry EEG Electrode. We are using Cyton Daisy hardware.
thanks
Comments
Have you seen this comment and thread regarding expected Ultracortex impedances?
https://openbci.com/forum/index.php?p=/discussion/comment/13328/#Comment_13328
So we should expect the impedance to be in range of 200k to 900k. However, our impedance values for some electrodes located near dense hair are high(2000k to 5000k range) and I think we are having trouble with the adjustment of electrodes. when we gently push the headset downward the electrodes touches the scalp and the reading of some channels improves.
Also, we can't really screw-in the electrodes after the participant wore the headset it twist their hairs and it can be uncomfortable.
So we were wondering if we need to follow some steps to successfully wear the headset especially for long hairs?
re: "Also, we can't really screw-in the electrodes after the participant wore the headset it twist their hairs and it can be uncomfortable."
I think you may be referring to a suggestion to gently 'rock' the electrode holder with a slight back and forth twist action. For example just a few degrees back and forth. This helps the teeth of the comb to move closer to the skin surface. Clearly you found if you actually twist more than this it will pull on the hair.
re: acceptable impedance range in hair areas. The link I gave said that 2M to 5M may be acceptable, if you acknowledge a small (less than 1%) error factor.
Thanks William it did work! I have a new problem though I'm creating a new discussion for that.