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Transient electrical behavior of an electrode/electrolyte interface based on a surface micro-structured with gold mushroom shapes

Reis, J. A. ; Medeiros, M. C. R. ; Gomes, H.L. ; Inácio, P.

Journal Applied Physics Vol. 124, Nº 21, pp. 214902 - 214902, December, 2018.

ISSN (print): 0021-8979
ISSN (online): 0021-8979

Scimago Journal Ranking: 0,75 (in 2018)

Digital Object Identifier: 10.1063/1.5042712

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The transient electrical behavior of an electrode/electrolyte interface based on an electrode micro-structured with gold protruding mushroom shapes is measured and modeled. The application of a voltage pulse train with changing frequency generates a corresponding train of current pulses with an offset current that approaches a saturation limit exponentially. The transient behavior of the electrical current was accurately reproduced using the Nernst-Planck-Poisson model and the geometric parameters of the mushroom shape. Spatiotemporal patterns of the electric field demonstrate that the current transient is caused by a slow kinetics of charges accumulating at the gold/electrolyte interface and under the micro-mushroom cap. The accumulation of charges establishes an internal electrical potential that drives a Faradic current through the mushroom/electrolyte interface. The aim of this work is to understand how this charge dynamics in the vicinity of the three-dimensional electrode surfaces is established and how it can be minimized to prevent damage to cells and tissues under electrical stimulation.