g.SAHARA’s active technology offers an amplifier inside the electrodes, where gel is applied between the electrode and the skin. The main advantage of gel-based active EEG electrodes is their robust signal quality, but this comes with a long mounting time and the need to wash the cap and the user’s hair after the recording too.
The newly developed and patented g.SAHARA Hybrid EEG technology can be used with and without gel. The g.SAHARA Hybrid EEG is made of a special conductive polymer. The pins have sufficient length to reach through the hair to the skin. The conductive polymer and the 8 pins reduce the electrode-skin impedance and give a solid contact to the skin.
Additionally, the electrode has a small hole in the middle to insert conductive electrode gel for wet recordings. This hybrid approach gives you a more stable EEG recording.
EEG recordings are performed at frontal, central, parietal and occipital regions of the head, and therefore a mechanical system is required that holds the electrode on the skin with a constant pressure at every possible recording location. EEG electrodes are typically positioned according to the international 10/20 system. g.tec hence developed the 2nd generation of the g.GAMMAcap, with a total of 160 positions according to an extended 10/20 system, to allow a very flexible electrode montage.
The design of the g.SAHARA Hybrid EEG electrodes allows users to just plug the electrode and the clip into the cap at any desired location.
|The first and only dry electrode system that works for all frontal, central, occipital, temporal and parietal sites|
|The first hybrid active eeg electrode available on the market|
|Allows dry and wet recordings with one electrode only|
|The first and only hybrid system successfully tested with all major BCI approaches in group studies, reported in peer-reviewed papers|
|Pick up frequency spectra for P300, Motor Imagery and SSVEP based BCIs|
|Same cost range as an active EEG electrode with gel – but works with and without gel|
|Captures the whole EEG frequency spectrum from 0.1-40 Hz|
|Mounting the cap in < 1 minute|
|No more need to wash the hair or cap|
|Amplification||Inside the electrode clip|
|Cables||Required 1.5 kV protection|
|Pin length||7 mm|
|Number of pins||8|
HYBRID WET & DRY EEG ELECTRODES
Recent studies showed that dry electrodes can pick up the corresponding frequency ranges of the EEG data for all three BCI principles (P300, Motor Imager and SSVEP). The subjects’ accuracy was about the same compared to gel EEG electrodes.
Nevertheless, dry electrodes are more sensitive to noise, movements of cables and electrostatic charges. Therefore, a careful cap montage, a well-controlled environment and a regular maintenance are important. Needless to say, there are situations where you might want wet EEG electrodes, such as g.GAMMAsys to allows your subject e.g. to move around during the recording. Active wet electrodes make recordings more stable and are easier to conduct.
The new g.SAHARA Hybrid technology combines both needs into one single electrode.