Comparison of three types of dry electrodes for electroencephalography

Abstract

A potential new area of routine application for electroencephalography (EEG) is the brain-computer interface, which might enable disabled people to interact with their environment, based on measured brain signals. However, conventional electroencephalography is not suitable here due to limitations arising from complicated, time-consuming and error-prone preparation. Recently, several approaches for dry electrodes have been proposed. Our aim is the comparison and assessment of three types of dry electrodes and standard wet silver/silver-chloride electrodes for EEG signal acquisition. We developed novel EEG electrodes with titanium and polyurethane as base materials, which were coated with nanometer sized titanium-nitride films. Furthermore gold multi-pin electrodes were arranged on printed circuit boards. The results of the comparison of these electrodes with conventional wet silver/silver-chloride electrodes in terms of electrode impedances are presented, as well as open circuit potentials and biosignal measurements. Impedances were significantly higher for all dry electrode types compared to wet electrodes, but still within the measurement range of today’s standard biosignal amplifiers. It was found that the novel dry titanium and polyurethane based electrodes show biosignal quality equivalent to conventional electrodes. In conclusion, the novel dry electrodes seem to be suitable for application in brain-machine interfaces.

Novel Multipin Electrode Cap System for Dry Electroencephalography

“…The shape of the dry-contact electrodes must enable the passing through of the hair layer and provide sufficient contact surface, reliability and stability, as well as patient comfort (Fiedler et al 2014). The developed electrode design consists of 24 single conic pins with circular tops of 1 mm in diameter and a height of 6 mm.…”

“…The centerto-center distances of the pins are 2.5 mm. The design is an improved version of our previously presented multipin electrodes (Fiedler et al 2014;Pedrosa et al 2015a).…”

“…Ag/AgCl is the gold standard material for wet electrodes and has outstanding electrochemical characteristics (Searle and Kirkup 2000;Fiedler et al 2014;Pedrosa et al 2015b). Thus, it has been selected for the electrically conductive coating of the multipin electrodes.…”

“…However, none of these concepts has so far been applied to multichannel EEG with more than 64 channels. We recently proposed multipin-shaped dry-contact electrodes that pass optimally through the hair layer (Fiedler et al 2014.…”

Desenvolvimento E Avaliação De Eletrodos Metálicos Passivos Para Eletromiografia De Superfície

“…Diversas topologias para eletrodos ativos têm sido sugeridas, com o objetivo de contornar este problema [1], [5], [6], [7], [8]. O maior esforço está em otimizar o circuito, sendo poucos estudos focados na influência do material na qualidade do sensor, embora a interface do eletrodo/pele seja o real fator limitante para os sistemas com eletrodos ativos [9].…”