A Flexible, Robust, and Gel-Free Electroencephalogram Electrode for Noninvasive Brain-Computer Interfaces

Abstract

Brain–computer interfaces (BCIs) enable direct and near-instant communication between the brain and electronic devices. One of the biggest remaining challenges is to develop an effective noninvasive BCI that allows the recording electrodes to avoid hair on human skin without the inconveniences and complications of using a conductive gel. In this study, we developed a cost-effective, easily manufacturable, flexible, robust, and gel-free silver nanowire/polyvinyl butyral (PVB)/melamine sponge (AgPMS) electroencephalogram (EEG) electrode that circumvents problems with hair. Because of surface metallization by the silver nanowires (AgNWs), the sponge has a high conductivity of 917 S/m while its weight remains the same. The flexible sponge framework and self-locking AgNWs combine to give the new electrode remarkable mechanical stability (the conductivity remains unchanged after 10 000 cycles at 10% compression) and the ability to bypass hair. A BCI application based on steady-state visual evoked potential (SSVEP) measurements on hairless skin shows that the BCI accuracy of the new electrode (86%) is approximately the same as that of conventional electrodes supported by a conductive gel (88%). Most importantly, the performance of the AgPMS on hairy skin is not significantly reduced, which indicates that the new electrode can replace conventional electrodes for both hairless and hairy skin BCIs and other EEG applications.

Nanowire‐Based Soft Wearable Human–Machine Interfaces for Future Virtual and Augmented Reality Applications

“…[ 15,170 ] However, most of current EEG electrodes are gel‐based Ag/AgCl wet electrodes; these electrodes suffer from various problems such as discomfort, allergy, and frequent recalibration. [ 171 ] Therefore, comfortable dry or semidry electrodes with high conductivity, good mechanical/chemical stability, and low interface impedance with skin are highly desired for next‐generation AR/VR EEG headsets.…”

“…Nanowire‐based highly conductive sponges may be a good choice as an EEG electrode because it can bypass hair on human skin to form intimate contact, which significantly reduces the skin‐electrode contact impedance. [ 171 ] As shown in Figure a, a semidry silver‐nanowire/polyvinyl butyral (PVB)/melamine sponge (AgPMS) electrode with a porous structure was used to collect the EEG signal. The AgNWs could easily penetrate the sponge's porous scaffold structures and wrap around the sponge skeletons.…”

Capturing Human Perceptual and Cognitive Activities via Event-Related Potentials Measured with Candle-Like Dry Microneedle Electrodes

“…Therefore, dry electrodes that can acquire EEG from hairy regions have been developed using unique materials, microfabrication techniques, and attachment mechanisms [9][10][11][12][13][14][15][16]. We developed candle-like dry microneedle electrodes (CMEs), as shown in Figure 1 [17].…”

Study on AgInZnS-Graphene Oxide Non-toxic Quantum Dots for Biomedical Sensing

“…HSA is broadly distributed in blood plasma. It has a significant effect on equilibrium osmotic pressure and transports various molecules in blood (Carter et al, 1989;Dong et al, 1990;Leckband, 2000;Lin et al, 2019a). Nanoparticles and drugs can bind with HSA for their exogenous ligand and is then transported into the body's circulatory system.…”