Miniaturized electroencephalographic scalp electrode for optimal wearing comfort

Introduction: Modern EEG electrode setups permit efficient recordings, but are often bulky and uncomfortable for subjects. Here we introduce a novel type of EEG electrode, which is designed for an optimal wearing comfort. The electrode is referred to as C-electrode where „C“ stands for comfort. Methods: The C-electrode does not require any holder/cap for fixation on the head nor does it use traditional pads/lining of disposable electrodes – thus, it does not disturb subjects. Fixation of the C-electrode on the scalp is based entirely on the adhesive interaction between the very light C-electrode/wire construction (<35mg) and a droplet of EEG paste/gel (patent pending). EEG recordings with standard and C-electrodes were performed during rest condition, self-paced movements and median nerve stimulation. Results: The quality of EEG recordings for all three types of experimental conditions was similar for standard and C-electrodes, i.e., for rest EEG spectra (1–45Hz), near-DC recordings (Bereitschaftspotential), and very fast oscillations ˜ 600Hz (somatosensory evoked potentials). The tests also showed that once being placed on a subject's head, C-electrodes can be used for nine hours without any loss in EEG recording quality. Furthermore, we also showed that C-electrodes can be effectively utilized for Brain-Computer Interfacing. C-electrodes proved to posses high stability of mechanical fixation (stayed attached with 2.5g accelerations). The impedance of C-electrodes can be <5 kOhm. Subjects also reported not having any tactile sensations associated with wearing of C-electrodes. Moreover, because of its miniaturization, both C-electrode (diameter 2–3mm) and its wire (diameter ˜ 50µm) are minimally (or not at all) visible to an external observer. This is important since routinely used bulky EEG holders/caps are usually associated with discomfort/unnecessary attention aroused either in the person wearing EEG electrodes or in persons who observe a subject with EEG electrodes. Discussion: C-electrodes provide optimal wearing comfort without any loss in the quality of EEG recordings. We anticipate that C-electrodes can be used in a wide range of clinical, research and emerging neuro-technological environments.