Multichannel EEG with novel Ti/TiN dry electrodes

• Published in: Sensors and actuators. A. Physical. 2015-01, Vol.221 (C), p.139-147
• Main Authors: Fiedler, P., Griebel, S., Pedrosa, P., Fonseca, C., Vaz, F., Zentner, L., Zanow, F., Haueisen, J.
• Format: Article
• Language: English
• Subjects: Actuator; Bioelectric signal; Consumption; Dry electrode; Drying; Electrodes; Electroencephalography; Electroencephalography (EEG); Multichannel; Multichannel cap; Recording; Silver; Titanium; Titanium nitride
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2014.10.010

•Novel, specifically shaped dry electrode and a novel compliant EEG cap design for multichannel AC-EEG.•Centrally, pump-driven mechanisms enable rapid, reproducible electrode adduction and reduced electrode-skin impedance level and variation.•Integration of novel dry and conventional gold standard electrodes into the cap enables direct comparison of signal quality.•In vivo EEG testing proved similar signal quality of the novel electrodes with considerably decreased preparation time and complexity. Research using multichannel electroencephalographic recordings is increasingly characterized by greater numbers of electrodes. With up to 256 silver/silver chloride (Ag/AgCl) electrodes, preparation and electrode placement is time consuming and error prone. We propose a novel type of dry titanium/titanium nitride (Ti/TiN) electrode, integrated into a novel electroencephalography (EEG) cap based on pneumatic-driven mechanisms. The electrodes were characterized electrochemically and comparative biosignal measurements were carried out. In a NaCl solution, the impedance values were between 824 and 54Ω and the phase values between –52 and –10° at frequencies between 5Hz and 10kHz for the Ti/TiN electrodes. For resting-state EEG, and with eye movements, alpha activity, and pattern reversal visual evoked potential (VEP), there were no significant differences between adjacent novel Ti/TiN and standard Ag/AgCl electrodes in 97.2% of the signal episodes investigated. The potential maps for pattern reversal VEP were similar with both types of electrodes. In conclusion, our novel cap system based on Ti/TiN electrodes and pneumatic-driven mechanisms enables completely dry EEG acquisition and can thus potentially replace conventional Ag/AgCl electrodes due to similar signal quality.