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 gel-based caps take longer to mount, and you need to wash the cap and the user’s hair after each recording.
The newly developed and patented g.SAHARA Hybrid EEG technology can be used with and without gel. You can choose! 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.
The g.SAHARA hybrid electrode can be used with g.HIamp and with the g.SAHARAbox with g.USBamp. 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|
|Cap mounting requires < 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|
Recent studies showed that dry electrodes can pick up the corresponding frequency ranges of the EEG data for all three major BCI approaches (P300, Motor Imagery and SSVEP/C-VEP). The subjects’ accuracy was about the same compared to gel EEG electrodes.
However, dry electrodes are more sensitive to noise, movement and electrostatic charges. Therefore, careful cap mounting, 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 allow your subject to move around during the recording. Active wet electrodes make recordings more stable. The new g.SAHARA Hybrid technology combines both needs into one single electrode.
g.GAMMAcap is an EEG cap designed for maximum comfort with minimal mounting time. The fabric used for this g.GAMMAcap is very flexible, but robust. 74 labeled standard positions (based on the extended 10-20 system / 10-10 system) and 86 additional intermediate positions are precut for easy placement. This makes it easy to configure caps for certain experiments (e.g. P300 speller, SSVEP robot control, high-density brain mapping, etc.).
All types of active and passive electrodes can be changed or replaced if necessary. The caps can be used with a chest belt strap or with chin straps, which are supplied with each cap. The caps, can be configured with electrodes for a certain experiment (such as the P300 speller), and the electrodes remain inside the cap even during cleaning. This makes preparation and cleaning very fast, which speeds up experiments considerably. A typical setup time for a P300 speller experiment (10 electrodes) is about 2 minutes – just put on the cap and inject the gel. After the cap is removed, the EEG gel almost disappears after some time, and gel is removed completely by washing the hair.
g.GAMMAcap fNIRS is an EEG cap edition that allows the additional montage of 8 fNIRS optodes. g.SENSOR fNIRS can be attached with a magnet to the cap and the optodes can be inserted into pre-defined positions over the sensorimotor-cortex and/or frontal cortex.
|Mini||Head circumference 32 - 36 cm|
|Midi||Head circumference 37 - 43 cm|
|Maxi||Head circumference 44 - 48 cm|
|Small||Head circumference 50 - 54 cm|
|Medium||Head circumference 54 - 58 cm (fits 95% of adult subjects)|
|Large||Head circumference 58 - 62 cm|
g.SAHARAbox is an EEG Electrode Connector Box that connects the fully equipped EEG cap with g.SAHARA Hybrid EEG electrodes with g.tec’s g.USBamp or g.HIamp biosignal amplifiers. If it is used with g.GAMMAclip ECG, EMG and EOG recordings are possible with active electrode technology. It is designed to make experimental setups for EEG/ECG/EMG/EOG recording fast and easy, and of highest quality.