Transparent electroencephalography? : Exploring ear-EEG for long-term, mobile electrophysiology

Multi-channel electroencephalography (EEG) is the most frequently used technology for brain-computer interface (BCI) and neurofeedback (NFB) applications, however it suffers from various limitations. Among others, the placement of electrodes on the scalp is distracting, time-consuming, uncomfortable, and it does not ensure good signal quality over extended periods of time. Moreover, the use of bulky amplifiers and wired connections to recording computers reduces the portability and mobility of BCI and NFB applications. In order to overcome these limitations, flex-printed disposable electrode arrays have been developed. The cEEGrid is a convenient-to-use array composed of 10 electrodes located around the ear. Results from several validation studies will be presented here, supporting the claim that around the ear EEG acquisition provides sufficient information to support BCI applications. When compared to cap-EEG, ear-EEG provides less spatial information but it facilitates long-term EEG acquisition in natural environments and thereby promises new avenues for EEG-BCI.