The EPOC collects EEG biosignals from 14 sensors around the head, plus 2 reference channels in CMS/DRL configuration. They are all EEG sensors. We have 8 sensors around the frontal and prefrontal lobes, which also by virtue of their location pick up signals from facial muscles and the eyes. In most EEG systems this is treated as a noise artefact and removed from the data. We also do the same for many of our detections, except we send the signals off to a classifier system which can pick out facial expressions such as smiling, chenching teeth, smirking, laughing, blinking, winking, raising and lowering eyebrows and horizontal glances.
There is no comparison between the EPOC and a 2-channel system or those with sensors placed only on the forehead. The amount of information gathered by the EPOC covers most of the active brain. The EPOC has slightly reduced voltage and time sensitivity compared to dedicated quasi-medical EEG systems but this is not an issue for most measurements.