- EEG electrode transforms ionic current into electrical current using pre-amplifiers.
- Silver - Silver chloride are commonly used in electrode disc.
- Reusable scalp disc or cup electrode are placed on head using conductive gel.
- The area is first cleaned with alcohol to remove skin oils.
- Amplitude frequency and phase of EEG depends on electrode placement.
- This placements include frontal, parietal, temporal and occipitinal cranial areas.
- The head is marked at four standard points nasion(nose), inion(back head) & left & right preauricular points(ears).
- Nineteen electrodes plus one for grounding is used.
- For EEG the electrodes are placed at 10%,20%, 20%, 20% and 10% from inion to nasion along lenght.
- Electrode is made either unipolar or bipolar form.
- Unipolar contains scalp-leads connected to common point like ear lobes.
- A bipolar scheme is available by interconnecting scalp electrodes.
Unipolar EEG recording mode:
Bipolar EEG recording mode:
Average EEG recording mode:
