Multi-Center Evaluation of Gel-Based and Dry Multipin EEG Caps

Abstract

Dry electrodes for electroencephalography (EEG) allow new fields of application, including telemedicine, mobile EEG, emergency EEG, and long-term repetitive measurements for research, neurofeedback, or brain–computer interfaces. Different dry electrode technologies have been proposed and validated in comparison to conventional gel-based electrodes. Most previous studies have been performed at a single center and by single operators. We conducted a multi-center and multi-operator study validating multipin dry electrodes to study the reproducibility and generalizability of their performance in different environments and for different operators. Moreover, we aimed to study the interrelation of operator experience, preparation time, and wearing comfort on the EEG signal quality. EEG acquisitions using dry and gel-based EEG caps were carried out in 6 different countries with 115 volunteers, recording electrode-skin impedances, resting state EEG and evoked activity. The dry cap showed average channel reliability of 81% but higher average impedances than the gel-based cap. However, the dry EEG caps required 62% less preparation time. No statistical differences were observed between the gel-based and dry EEG signal characteristics in all signal metrics. We conclude that the performance of the dry multipin electrodes is highly reproducible, whereas the primary influences on channel reliability and signal quality are operator skill and experience.

Development of Low-Contact-Impedance Dry Electrodes for Electroencephalogram Signal Acquisition

“…Dry EEG systems have a short set-up time, require limited hair preparation, and do not require skin scrubbing, as required by a wet EEG system [23]. The electrodes used in dry EEG systems are commonly called dry electrodes because they are gel-free.…”

Simultaneous Dry and Gel-Based High-Density Electroencephalography Recordings

“…Dry electrodes have several advantages over gel-based electrodes. For example, EEG caps with dry electrodes can be self-applied and easily used in settings outside a laboratory or clinic [ 2 , 18 , 19 ]. Their preparation and cleaning times are considerably shorter, especially for higher numbers of channels [ 2 , 18 ].…”

“…For example, EEG caps with dry electrodes can be self-applied and easily used in settings outside a laboratory or clinic [ 2 , 18 , 19 ]. Their preparation and cleaning times are considerably shorter, especially for higher numbers of channels [ 2 , 18 ]. However, currently, channel dropout rates are higher for dry electrode recordings [ 2 , 18 ], and they are more prone to movement artifacts [ 12 ].…”

“…Their preparation and cleaning times are considerably shorter, especially for higher numbers of channels [ 2 , 18 ]. However, currently, channel dropout rates are higher for dry electrode recordings [ 2 , 18 ], and they are more prone to movement artifacts [ 12 ]. Thus, it is important to test the performance of the dry electrodes in direct comparison with the gold standard electrodes.…”

“…Thus, it is important to test the performance of the dry electrodes in direct comparison with the gold standard electrodes. In addition to mechanical, electrical, and chemical characterizations of both types of electrodes [ 10 , 15 , 19 ], comparisons in studies with human volunteers are important to assess electrode performance under realistic conditions and for distinct applications like laboratory settings in research [ 1 , 2 , 3 , 4 , 5 , 11 , 12 , 13 , 18 ] and clinical diagnostics [ 6 ], emergency applications [ 20 , 21 ], brain–computer interfacing [ 22 , 23 ], home settings [ 16 ], or mobile recordings in, for example, sports and movement sciences [ 24 , 25 ]. Each of these applications poses specific requirements for the sensors and sensor applicators, but across all of them, ensuring objective comparison metrics, reproducibility, and minimizing the impact of not sensor-related influences and parameters are key aspects during study design.…”