Title: Coulometric Detection of Irreversible Electrochemical Reactions Occurring at Pt Microelectrodes Used for Neural Stimulation
Authors: Musa, Silke ×
Rand, Danielle R
Bartic, Carmen
Eberle, Wolfgang
Nuttin, Bart
Borghs, Gustaaf #
Issue Date: Jun-2011
Publisher: Amer chemical soc
Series Title: Analytical Chemistry vol:83 issue:11 pages:4012-4022
Abstract: The electrochemistry of 50 mu m diameter Pt electrodes used for neural stimulation was studied in vitro by reciprocal derivative chronopotentiometry. This differential method provides well-defined electrochemical signatures of the various polarization phenomena that occur at Pt microelectrodes and are generally obscured in voltage transients. In combination with a novel in situ coulometric approach, irreversible H-2 and O-2 evolution, Pt dissolution and reduction of dissolved O-2 were detected. Measurements were performed with biphasic, charge-balanced, cathodic-first and anodic-first current pulses at charge densities ranging from 0.07 to 1.41 mC/cm(2) (real surface area) in phosphate buffered saline (PBS) with and without bovine serum albumin (BSA). The extent to which O-2 reduction occurs under the different stimulation conditions was compared in O-2-saturated and deoxygenated PBS. Adsorption of BSA inhibited Pt dissolution as well as Pt oxidation and oxide reduction by blocking reactive sites on the electrode surface. This inhibitory effect promoted the onset of irreversible H-2 and O-2 evolution, which occurred at lower charge densities than those in PBS. Reduction of dissolved O-2 on Pt electrodes accounted for 19-34% of the total injected charge in O-2-saturated PBS, while a contribution of 0.4-12% was estimated for in vivo stimulation. These result may prove important for the interpretation of histological damage induced by neural stimulation and therefore help define safer operational limits.
ISSN: 0003-2700
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Solid State Physics and Magnetism Section
Research Group Experimental Neurosurgery and Neuroanatomy
Semiconductor Physics Section
× corresponding author
# (joint) last author

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