What do the electrodes look like?
Here's some quick pictures to give you an idea. They are very basic, but they give you a good quick idea.
 |
 |
 |
3 silver electrodes are connected to a specialized EEG amplifier. The electrodes, after being placed on the head, will detect the very tiny electrical signals generated by the brain, and send them to the EEG amplifier. The signals are millionths of a volts (microvolts) at the scalp. The EEG amplifier must take that signal, multiple it and send it to the computer where it's interpreted and displayed by special software. We prefer using the best possible amplifier (more expensive). The amplifier is responsible for the integrity of the signal. Like a radio trying to tune into a far away station (the signal from the cortex), the more accurately and sensitively that signal is read and amplified, the clearer the information the brain will receive about itself. |
Notice the yellow electrode now has paste. That's a flat electrode. It will be placed at directly at a site on the head. The wax or paste is electrically conductive. The ear clips (like earrings) are placed on the ear lobe. They also must use the same electrically conductive paste. The paste allows the tiny electrical signal to be more easily read. Rather than having 2 ear clips and 1 flat electrode, you can also have 1 ear clip and 2 electrodes on the head. That's one EEG channel. |
This is the flat electrode with paste about to be placed at C4 (right side of head). We always recommend that the site be prepped (scrubbed with an abrasive such as nu-prep) prior to sticking the electrode on the scalp. That helps minimize any noise (dirty signal) from getting into the feedback. We also recommend when the electrode is placed, a measurement be made to insure a quality connection. |
 |
 |
| Here's the ear clip with paste about to be placed. We recommend the ears also be prepped with an abrasive to insure a consistent signal and connection. | Here's an electrode placed at about C4 (it's a little high, actually). The other end is connected the amplifier. In this case, there's not too much hair to worry about. In most cases, the placement needs to be made carefully, so there's not much hair underneath the electrode. It needs a good connection with the skin. Even with the thickest hair, it is still possible to get a good connection. |