Ubiquitous Brain Computer Interfaces Based on Ear EEG Electrodes

Brain computer interface (BCI) designs have traditionally focused on the use of electrodes located on the scalp of a person to measure their brain activity using Electroencephalography (EEG) brain imaging techniques. Scalp EEG traditionally utilized metal electrodes placed over the scalp with conductive gel between the electrode and the skin to improve electrical contact. Dry contact electrodes were then developed to make the process more user-friendly and to reduce the time to setup EEG systems before conducting experiments. This made EEG more accessible outside of research and medical laboratories and led to the release of BCI products onto the consumer market. Despite the recent advances in invasive BCI’s based on implants, dry electrode EEG offers a greater ability to develop EEG products for daily use. One of the most important product challenges to over-come is the design of BCI’s which fit into existing societal trends. Scalp-focused BCI designs are difficult to scale beyond niche user communities since they represent another device for users to integrate into their lives. Ear EEG offers a way to design BCI products that integrate into users’ lives similar to the way that earbuds have seen wide adoption across different cultures and markets throughout the world.
IDUN Technologies has developed electrodes for biopotential measurements since 2017. The IDUN Guardian Development Kit BCI relies on ear EEG electrodes in an earbud form-factor to facilitate the research of ear EEG for applications from sleep and wellness to acoustic attention. The IDUN ear EEG electrodes are based on a conductive polymer formed into traditional earbud shapes. The combination of electrical conductivity and mechanical deformability allow the electrodes to provide secure contact to the surface of the ear canal resulting in good signal quality for EEG measurements. Performance of the system has been evaluated with electrical impedance as well as EEG paradigm measurements. The mean in-ear skin-contact impedances of the ear electrodes tested in humans at 10 Hz ranged from 11 kΩ to 190 kΩ with a mean of 75 kΩ for cleaned and of 110 kΩ for uncleaned ears. EEG paradigm validation has been conducted included Acoustic Steady State Response (ASSR), Alpha excitation and sleep features includes slow waves and spindles.