State of the Art of Non-Invasive Electrode Materials for Brain–Computer Interface

Abstract

The brain–computer interface (BCI) has emerged in recent years and has attracted great attention. As an indispensable part of the BCI signal acquisition system, brain electrodes have a great influence on the quality of the signal, which determines the final effect. Due to the special usage scenario of brain electrodes, some specific properties are required for them. In this study, we review the development of three major types of EEG electrodes from the perspective of material selection and structural design, including dry electrodes, wet electrodes, and semi-dry electrodes. Additionally, we provide a reference for the current chaotic performance evaluation of EEG electrodes in some aspects such as electrochemical performance, stability, and so on. Moreover, the challenges and future expectations for EEG electrodes are analyzed.

Intelligent Headband System for Evaluating Rehabilitation Effectiveness

“…The use of dry of Ag/AgCl and Ag-plated Cu electrodes for signal acquisition improves the convenience of use and effectively prevents the problem of conductive gels hardening. However, the dry electrodes may undergo oxidation, causing higher contact impedance [54] and affecting EEG signal acquisition. Moreover, this technique is suitable for functional brain activity observation [55] but cannot be used to assess cerebral blood circulation.…”

Design of hydrogel-based wearable EEG electrodes for medical applications

“…Other conducting materials, such as gold and microporous titanium, [94][95][96] conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), [97][98][99] carbon nanotubes (CNTs), 100 and graphene, [101][102][103] have also been investigated for their possible use in EEG electrodes. For example, Leleux et al fabricated a flexible EEG electrode via depositing PEDOT:PSS on a polyimide substrate and obtain a signal-to-noise ratio (SNR) of 24.4 dB when measuring the somatosensory evoked potentials (Fig.…”

Bioactive polymer-enabled conformal neural interface and its application strategies

“…19–21 In these studies, the role of the electrode has been found to be essential in neural interface technology, where its performance can directly affect the quality of signal acquisition and the efficiency of signal processing. 22…”

“…[19][20][21] In these studies, the role of the electrode has been found to be essential in neural interface technology, where its performance can directly affect the quality of signal acquisition and the efficiency of signal processing. 22 Throughout the history of neural interfaces, material and structural innovations are two key factors that drive the advances in neural interfaces (see Fig. 1).…”