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Title: Electrochemical and mechanical performance of reduced graphene oxide, conductive hydrogel, and electrodeposited Pt-Ir coated electrodes: an active in vitro study
Authors: Dalrymple, Ashley
Huynh, Mario
Robles, Ulyises
Marroquin, Jason
Lee, Curtis
Petrossians, Artin
Whalen, John
Li, Dan
Parkington, Helena
Forsythe, John
Green, Rylie
Poole-Warren, Laura
Shepherd, Robert
Fallon, James
Keywords: Electrical stimulation
Neural prosthesis
Electrode
In vitro
Platinum
Conductive hydrogel
Reduced graphene oxide
Electrodeposited Pt-Ir
Corrosion
Issue Date: Oct-2019
Publisher: IOP Publishing
Citation: Dalrymple, A. N., M. Huynh, U. A. Aregueta Robles, J. B. Marroquin, C. Lee, A. Petrossians, J. J. Whalen, D. Li, H. C. Parkington, J. S. Forsythe, R. Green, L. A. Poole-Warren, R. K. Shepherd, and J. B. Fallon. 2019. Electrochemical and mechanical performance of reduced graphene oxide, conductive hydrogel, and electrodeposited Pt-Ir coated electrodes: an active in vitro study. Journal of Neural Engineering: [epub ahead of print].
Abstract: OBJECTIVE: To systematically compare the in vitro electrochemical and mechanical properties of several electrode coatings that have been reported to increase the efficacy of medical bionics devices by increasing the amount of charge that can be delivered safely to the target neural tissue. APPROACH: Smooth platinum (Pt) ring and disc electrodes were coated with reduced graphene oxide, conductive hydrogel, or electrodeposited Pt-Ir. Electrodes with coatings were compared with uncoated smooth Pt electrodes before and after an in vitro accelerated aging protocol. The various coatings were compared mechanically using the adhesion-by-tape test. Electrodes were stimulated in saline for 24 hours/day 7 days/week for 21 days at 85 masculineC (1.6-year equivalence) at a constant charge density of 200 muC/cm2/phase. Electrodes were graded on surface corrosion and trace analysis of Pt in the electrolyte after aging. Electrochemical measurements performed before, during, and after aging included electrochemical impedance spectroscopy, cyclic voltammetry, and charge injection limit and impedance from voltage transient recordings. MAIN RESULTS: All three coatings adhered well to smooth Pt and exhibited electrochemical advantage over smooth Pt electrodes prior to aging. After aging, graphene coated electrodes displayed a stimulation-induced increase in impedance and reduction in the charge injection limit (p < 0.001), alongside extensive corrosion and release of Pt into the electrolyte. In contrast, both conductive hydrogel and Pt-Ir coated electrodes had smaller impedances and larger charge injection limits than smooth Pt electrodes (p < 0.001) following aging regardless of the stimulus level and with little evidence of corrosion or Pt dissolution. SIGNIFICANCE: This study rigorously tested the mechanical and electrochemical performance of electrode coatings in vitro and provided suitable candidates for future in vivo testing.
URI: http://repository.bionicsinstitute.org:8080/handle/123456789/370
ISSN: 1741-2552
Appears in Collections:Other research publications

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