Normally, the electroencephalogram (EEG) is recorded from the surface of the head with gel based electrodes to get a low electrode-skin impedance. If passive electrodes are used, the skin must be abraded beforehand to reduce the impedance. With active electrodes, which contain an amplifier inside, the electrode gel is injected between the electrode material and the skin. This allows a faster montage of the electrode system.

One of the main advantages of gel based active electrodes is their robust behavior, but the main disadvantages are the long montage time and the need to wash the user’s hair after the recording. g.tec thus developed a dry electrode system which does not require electrode gel. The g.SAHARA electrode system (patent pending) consists of an 8 pin electrode made of a special gold alloy. The pins have sufficient length to reach through the hair to the skin. The material and the 8 pins reduce the electrode-skin impedance. The electrode itself can be connected with a clip to the active electrode system on top of it.

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 to 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 first and only dry electrode system that works for all frontal, central, occipital and parietal sites
• he first dry active electrode already available on the market
• The first and only dry system tested with all major BCI concepts in group studies with success
• Cost range of an active EEG electrode
• Captures the whole EEG frequency spectrum from 0.1-40 Hz
• Perform EEG recordings without gel
• Mount the cap in under one minute!
• Washing hair is no longer required!
• Able to pick up frequency spectra for P300, motor imagery and SSVEP based BCIs