Validation of soft multipin dry EEG electrodes

Background: Current developments towards multipin, dry electrodes in electroencephalography (EEG) are promising for applications in non-laboratory environments. Dry electrodes do not require the application of conductive gel, which mostly confines the use of gel EEG systems to the laboratory environment.
Aim: The aim of the current study is to validate soft, multipin, dry EEG electrodes by comparing their performance to conventional gel EEG electrodes.
Methods: 15 healthy volunteers performed three tasks, with the 32-channel gel EEG system and the 32-channel dry EEG system: the 40Hz Auditory Steady-State Response (ASSR), the checkerboard paradigm, and the eyes open/closed task. Within-subject analyses were performed to compare the signal quality in time, frequency and spatial domain.
Results: The results showed strong similarities between the two systems in time and frequency domain, by strong correlations of the visual (ρ=0.89) and auditory evoked potential (ρ=0.81), and moderate to strong correlations for the alpha band during eyes closure (ρ=0.81-0.86) and the 40Hz-ASSR power (ρ=0.66-0.72), respectively. However, delta and theta band power was significantly increased, and the signal-to-noise ratio was significantly decreased for the dry EEG system. Topographical distributions were comparable for both systems. Application time of the dry EEG system was significantly decreased with 8min.
Conclusion: It can be concluded that the soft, multipin dry EEG system can be used brain activity research with similar accuracy as conventional gel electrodes.