BME.03 – Inclusive Electroencephalogram (iEEG)

• Giorgia Asamoah
• Aussten Hayes
• Madeline Simmons
• Abdul Syed
• Elizabeth Wynn

Electroencephalograms are used in neuroscience research to measure brain signals and interpret the information received from the signals. Many different devices are used to record EEG signals like the traditional EEG cap, which covers the whole head like a swim cap, or the now popular Emotiv EPOC X with fixed electrode arm placements. These devices are unable to provide the same level of accuracy and precision when measuring signals from participants with curlier hair textures and larger heads compared to testing on participants with straighter, thinner hair. This issue is due to the devices not having enough modularity and adjustability to be compatible with all hair types causing a disparity in research that excludes participants with natural hairstyles, specifically Black participants. Our device addresses this disparity by incorporating adjustability into the design to ensure our device is inclusive and able to fit comfortably and function properly on all hair types, hairstyles, and head sizes. The device contains three components: the headband, plastic snap buttons, and electrode arms. The headband is a double-layered sewn 1 inch non-roll elastic band with a cavity between layers for wiring, and a plastic buckle for easy placement and improved adjustability from 53 to 58 cm unstretched. Forty-three centimeters of the headband allows for 18 button placements with evenly spaced 0.3 cm sewn and 2 cm non-sewn segments. The non-sewn segments have buttons centered to the width of the band and allow the wire to exit adjacent to the buttons. The electrode arms include lengths of 5, 25, and 45 mm which are printed in PLA for stiffer tension, and 60 and 90 mm which are printed in PETG for more flexibility. The other half of the button is superglued to the electrode arm, which then connects to the headband. Verification of the design was conducted in two stages, the first involved generating an electrochemical impedance spectroscopy plot and finding the average impedance of five electrode pairs with a 200mV and 10 Hz input. This resulted in a characteristic EIS plot with an equivalent circuit of a resistor and capacitor and an average impedance of 1162.8 ohms. The second stage involved placing two electrodes 4 cm apart on the forearms and scalps of participants, imputing a 200mV and 10 Hz waveform, and measuring the impedance of the forearm and scalp. Participants self-reported hair types or style and the impedances were sorted accordingly. ANOVA of the groups found a p-value of 0.2461, rejecting the null and showing no significant difference in impedance across hair types and styles. Our device increases inclusivity by allowing for adjustability and modularity, as well demonstrating similar impedances across hair types and styles. This allows for increased diversity in EEG studies by allowing for use on braids, locks, and other commonly excluded hair types.