A Study on Electrode Positions Around the Ear for BCI Development using SSVEP

Abstract

In recent years, with the advent of wearable EEG devices, brain-computer interface (BCI) has become popular not only in the medical field but also for general use. Conventional wearable EEG devices are mainly worn on the head, which induces discomfort when worn for a long time and is unattractive. The area around the ear can be considered as a measurement site that solves these problems and is easy to wear. However, there is still little knowledge about EEG around the ear, and the appropriate measurement site has not been determined. In this study, we investigated the optimal electrode placement and EEG recording method around the right ear for steady-state visual evoked potential (SSVEP), which has a high signal-to-noise ratio among EEGs used in BCI. Electrodes were attached to Pz, Oz, and eight locations around the right ear, and measurements were performed using unipolar and bipolar leads. The cross-correlation coefficients between Pz, Oz, and the electrodes around the right ear were calculated, and two locations with particularly high values were identified. In addition, by calculating the EEG data combination from multiple channels around right ear, some channel combinations were found which can significantly improve the discrimination accuracy of BCI system.