Towards an EEG cap: A study of electrode ability under non ideal conditions

Author: . Roshan Fedric Coelho

Roshan Fedric Coelho, ., 2019 Towards an EEG cap: A study of electrode ability under non ideal conditions, Flinders University, College of Science and Engineering

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Introduction: The absence of definitive data and EEG acquisition methods to diagnose schizophrenia and bipolar disorder (BP) is seen to be a hindrance in the early treatment and management of the diseases. A primary concern in the existing field of studies, shows the absence of data showing the differentiation of EEG patterns between schizophrenia and BP. This thesis aims at experimenting with the effectiveness of different electrode types under non-ideal conditions, towards building a new EEG cap, that will be used to diagnose schizophrenia and BP.

Methods: Thesis first experimented on 3 willing subjects, with varying degrees of hair volume and type, acquired EEG data off the participants and then visualized the data by running it through pre-existing code, before analysis was done by the author. The experiments attempted to place electrode types on at least 2 subjects per experiment, in order to increase sample size as well as compare effects of hair. The primary outcome measure was the successful acquisition of neural biology from a non-ideal electrode setup.

Results/Discussion: Data from experiments show us the effectiveness of wet passive electrode system over others, and draws special interest to tCRE electrodes which show the ability to ignore the effects of muscle on the acquired EEG. Combination of wet and dry electrodes also showed evidence of neural activity. Berger effect was used to compare muscle seen in the software laplacian of the EEG acquired and the acquired EEG itself. This allowed for a visual study of areas of interest.

Conclusion: Our study found that wet passive electrodes were best suited to non-ideal conditions, due to their ability to maintain contact with the scalp under duress. A combination of dry and wet electrodes was also seen to show some promise and required further experiments to confirm efficacy. tCREs were especially noted to be able to acquire data under difficult conditions. The use of tCREs also reduced the number of electrodes required for clinical EEG, from 128 to about 4-8 depending on the area of interest. Additionally, hair was seen to be major factor in the successful acquisition of data, not only with regard to volume, but also type. Future studies are expected to improve on sample size, electrode types their combinations and conclusively lay framework for the electrodes used in the EEG cap.

Keywords: Clinicial EEG, EEG, Schizophrenia, Bipolar Disorder, Muscle in EEG, ICA, EEG Experiments, Muscle Tasks, Alpha peak, Alpha waves, Laplacian of EEG, dry electrodes, passive electrodes, SAHARA electrodes, comb electrodes, EEG electrodes, EEG cap, Berger effect

Subject: Health Sciences thesis

Thesis type: Masters
Completed: 2019
School: College of Science and Engineering
Supervisor: Kenneth J. Pope