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Flexible film and breathable textile electrodes for electrodermal activity monitoring

University of British Columbia

The field of research on wearable systems that monitor human biological responses for healthcare applications is constantly advancing. Electrodermal activity (EDA) is related to the neurological system and is a result of the autonomic nervous system being stimulated, which produces sweat on the surface of the skin, thereby changing its electrical characteristics. The current clinical devices used to monitor EDA utilize rigid and non-breathable silver/silver chloride (Ag/AgCl) electrodes, possibly in combination with gels and irritating adhesives. The research detailed in this dissertation is focused on advancing our understanding of the design and development of comfortable, flexible and breathable EDA electrodes. Flexible dry Ag/AgCl electrodes were fabricated on a compliant substrate with various surface areas, distances between and geometries. The flexible electrodes were systematically characterized to determine their ability to detect EDA stimulus responses and these were compared to the responses simultaneously collected by rigid dry Ag/AgCl electrodes. The data demonstrated that surface area, spacing and geometry of electrodes affected the detection of the EDA stimulus response. The minimum number of sweat glands to be covered by flexible EDA electrodes has been estimated at 140 to maintain functionality. The optimal design of flexible electrodes is a serpentine geometry (0.15 cm² surface area, 0.20 cm distance). Ag/AgCl electronic yarns were developed through a novel roll-to-roll system and integrated into textile substrates of cotton, nylon and polyester. The EDA stimulus responses detected by dry electronic textile (e-textile) electrodes at various locations on the hand were compared to the EDA signals collected by dry solid Ag/AgCl electrodes. The cotton textile substrate with e-textile electrodes (0.12 cm² surface area, 0.40 cm distance) was the optimal material to detect the EDA stimulus responses. Also, differences with EDA waveforms recorded on various fingers were observed. Trends of long-term measurements showed that skin surface temperature affected EDA signals recorded by non-breathable electrodes more than when e-textile electrodes were used. The effects of electrode design and material for flexible and breathable EDA electrodes detailed in this dissertation can promote the development of effective and wearable EDA monitoring systems, which can help improve our knowledge of the human neurological system.

Text

2018-08-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/66824

Biomedical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/