Ear-EEG

Ear-EEG is a method for measuring dynamics of brain activity through the minute voltage changes observable on the skin, typically by placing electrodes on the scalp.

In ear-EEG, the electrodes are exclusively placed in or around the outer ear, resulting in both a much greater invisibility and wearer mobility compared to full scalp electroencephalography (EEG), but also significantly reduced signal amplitude, as well as reduction in the number of brain regions in which activity can be measured.

And in this context, it is very important to perform detailed comparisons between ear-EEG and regular scalp EEG, as results need to be comparable across platforms.

Because no gel is applied to the electrodes, the user can potentially mount the ear-EEG device without assistance.

[29][22] The compact and discreet nature of ear-EEG devices makes it suitable for real-life EEG monitoring.

[34][35] A promising use case is in long-term sleep monitoring, where there is presently a need for a more user friendly (and cheaper) alternative to the gold standard polysomnography.

Foremost of these are the hearing aid producers Oticon [43] and Widex and its sister company T&W Engineering,[44] who are looking into hearing-aid applications, the feasibility of which there appears to be some support for,[45][46] and a hypoglycemia alarm.

Demonstration of multiple cEEGrids on dummy heads
Example of a scalp topography (middle) with corresponding ear-topographies (left and right). The topographies show the potential on the scalp and in the ears for a single dipolar brain source and were calculated using an individualized ear-EEG forward model as described by Kappel et al. [ 18 ]
High-density ear-EEG.
Example of high-density ear-EEG. On the left is seen a high-density ear-EEG earpiece mounted in the ear. On the right is a picture of a high-density ear-EEG soft-earpiece with dry-contact electrodes. [ 24 ] [ 25 ]