An In-Laboratory Comparison of FocusBand EEG Device and Textile Electrodes Against a Medical-Grade System and Wet Gel Electrodes

Matias Rusanen,Juha Töyräs,Laura Kalevo,Timo Leppänen,Katja Myllymaa,Samu Kainulainen,Sami Myllymaa

doi:10.1109/access.2021.3113049

Matias Rusanen, Juha Töyräs + Show 5 more

Open Access

https://doi.org/10.1109/access.2021.3113049

Copy DOI

Abstract

In this study, FocusBand’s textile electrodes were tested against medical-grade wet electrodes to investigate the possible differences in skin-electrode interface behavior and EEG signals’ quality. In vivo electrical impedance spectroscopy and simultaneous forehead EEG measurements were performed with ten healthy subjects. In addition, the FocusBand device was tested in a stand-alone manner against a medical-grade reference system using similar test measurements. Compared to wet electrodes, textile electrodes had higher median absolute skin-electrode impedances five minutes after the attachment, but this difference decreased to 50–55 % of the initial during the first 60 minutes on all measured frequencies (1–1000 Hz). Textile and wet electrodes produced highly consistent EEG signals at forehead Fp1 and Fp2 locations during a resting stage and focusing measurements. From those, Fp1 signals were more consistent in terms of normalized cross-correlations and agreement of the relative spectral powers. A stand-alone comparison showed that the FocusBand device can be used to record forehead biopotential signals, but the quality was not as consistent as with a medical device. Based on the results of impedance characteristics, a recording made by FocusBand’s textile electrodes may be more susceptible to artifacts than that made by the medical-grade wet electrodes. However, FocusBand’s textile electrodes can be used, after a short stabilization period, to reliably record forehead EEG signals with a quality almost equal to that of medical-grade wet electrodes.

Highlights

Electroencephalography (EEG) is the most common measurement technique for recording the electrical activity of the brain
We quantitatively evaluate the signal quality of a wearable headband (FocusBand Technologies, T 2 Green Pty Ltd., Windaroo, Australia), which includes three silver oxide textile electrodes, originally intended for neurofeedbackoriented sports training
The FocusBand’s textile electrodes can be used, after a short stabilization period, to reliably record forehead EEG. This conclusion is based on the revealed skin-electrode interface behavior and EEG signal quality of the textile electrodes when compared to a medical-grade reference

Summary

Introduction

Electroencephalography (EEG) is the most common measurement technique for recording the electrical activity of the brain. EEG is a compulsory part of polysomnography (PSG) to detect sleep stages and cortical arousals [1]. Current medically approved EEG/PSG devices with accompanying sensor technologies still possess many disadvantages in terms of portability, costs, and ease of use, negatively affecting the availability of the measurement [2]. As sleep studies including EEG are mainly restricted to the laboratory environment, other disadvantages of PSG include a general deterioration in normal sleep structure and a typical onenight measurement [2]. As the demand for sleep studies is increasing due to growing awareness of sleep disorders [3], new wearable solutions for measuring EEG outside the sleep laboratories are urgently needed.

Objectives

Methods

Results

Discussion

Conclusion