The most commonly employed electrodes for recording electroencephalographic signals from the brain (EEG) are cup electrodes and subdermal needle electrodes. Cup electrodes are fabricated from platinum or tin approximately 5-10 mm in diameter. These cup electrodes are filled with a conducting electrolyte gel and can be attached to the scalp with adhesive tape.
Recording of electrical potentials from the scalp is cumbersome because hair and oily skin impede good electrical contact. Hence, clinicians sometimes prefer to use subdermal EEG electrodes instead of metal surface electrodes for EEG recording. These are essentially fine platinum or stainless-steel needle electrodes about 10 mm long by 0.5 mm wide, which are inserted under the skin to provide a better electrical contact.
Related: ECG Electrodes
