  In the past few years it has been demonstrated that electroencephalography
(EEG) can be recorded from inside the ear (in-ear EEG). To open the door to
low-profile earpieces as wearable brain-computer interfaces (BCIs), this work
presents a practical in-ear EEG device based on multiple dry electrodes, a
user-generic design, and a lightweight wireless interface for streaming data
and device programming. The earpiece is designed for improved ear canal contact
across a wide population of users and is fabricated in a low-cost and scalable
manufacturing process based on standard techniques such as vacuum
forming,plasma-treatment, and spray coating. A 2.5x2.5 cm^2 wireless recording
module is designed to record and stream data wirelessly to a host computer.
Performance was evaluated on three human subjects over three months and
compared with clinical-grade wet scalp EEG recordings. Recordings of
spontaneous and evoked physiological signals, eye-blinks, alpha rhythm, and the
auditory steady-state response (ASSR), are presented. This is the first
wireless in-ear EEG to our knowledge to incorporate a dry multielectrode,
user-generic design. The user-generic ear EEG recorded a mean alpha modulation
of 2.17, outperforming the state-of-the-art in dry electrode in-ear EEG
systems.
