Validation of Electroencephalographic Recordings Obtained with a Consumer-Grade, Single Dry Electrode, Low-Cost Device: A Comparative Study.

Héctor Rieiro,Samuel Romero,Andrés Catena,Carolina Diaz-Piedra,Joaquin Roca-Gonzalez,José Miguel Morales,Leandro L. Di Stasi,Luis J. Fuentes

doi:10.3390/s19122808

Abstract

The functional validity of the signal obtained with low-cost electroencephalography (EEG) devices is still under debate. Here, we have conducted an in-depth comparison of the EEG-recordings obtained with a medical-grade golden-cup electrodes ambulatory device, the SOMNOwatch + EEG-6, vs those obtained with a consumer-grade, single dry electrode low-cost device, the NeuroSky MindWave, one of the most affordable devices currently available. We recorded EEG signals at Fp1 using the two different devices simultaneously on 21 participants who underwent two experimental phases: a 12-minute resting state task (alternating two cycles of closed/open eyes periods), followed by 60-minute virtual-driving task. We evaluated the EEG recording quality by comparing the similarity between the temporal data series, their spectra, their signal-to-noise ratio, the reliability of EEG measurements (comparing the closed eyes periods), as well as their blink detection rate. We found substantial agreement between signals: whereas, qualitatively, the NeuroSky MindWave presented higher levels of noise and a biphasic shape of blinks, the similarity metric indicated that signals from both recording devices were significantly correlated. While the NeuroSky MindWave was less reliable, both devices had a similar blink detection rate. Overall, the NeuroSky MindWave is noise-limited, but provides stable recordings even through long periods of time. Furthermore, its data would be of adequate quality compared to that of conventional wet electrode EEG devices, except for a potential calibration error and spectral differences at low frequencies.

Highlights

Electroencephalography (EEG), since its invention in the early 1900s [1], has been one of the most commonly used techniques for neurological and psychological assessments
The results presented here give an accurate representation of the strengths and limits of the MindWave recording device, and delineate the most appropriate scenarios for its use in scientific applications
The blink detection rates do not differ between the two recording devices, the amplitude of EEG oscillations in the alpha band are, as expected, different between closed eyes and open eyes for both devices, and signals coming from both devices can be considered reliable, even though reliability is lower for the MindWave

Summary

Introduction

Electroencephalography (EEG), since its invention in the early 1900s [1], has been one of the most commonly used techniques for neurological and psychological assessments. Sensors 2019, 19, 2808 maximize the signal-to-noise ratio, and using multiple electrodes (32, 64, 128, or more—usually reusable—embedded in a stretch-lycra electrode cap or pasted to the scalp) These expensive devices (with prices ranging from $5,000 to $50,000) restrict data collection to controlled laboratory environments, requiring participants to be physically tethered to them. In the past ten years new EEG devices [10] and processing algorithms [11] have appeared that overcome many of these barriers (for a recent review on this topic, see [12]) Their improved design offers simple arrangements that do not limit participants’ behavior and are easy to set up by researchers and general public, as they require little to no training [13,14,15]

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