 This system is based on seven dry electrodes that can measure brainwaves millimeters from the scalp and thus can easily be worn over hair.These sensors are a significant technological breakthrough in that they are the only non-contact EEG sensors ever developed.These sensors have been effectively used with SSEVP (steady-state visually evoked potential) allowing a device incorporating them to tell which object, out of a set group of objects, the wearer is looking at.