Scanning electron microscopy of chronically stimulated platinum intracochlear electrodes

doi:10.1016/0142-9612(85)90019-5

Biomaterials

Volume 6, Issue 4, July 1985, Pages 237-242

https://doi.org/10.1016/0142-9612(85)90019-5 Get rights and content

Abstract

Platinum electrodes were examined for evidence of corrosion using a scanning electron microscope (SEM). In vivo electrodes, stimulated using charge-balanced biphasic pulses for periods of up to 2000 h at charge densities of 0.18–0.32 μC mm⁻² geom. per phase, were compared with in vitro electrodes stimulated in inorganic saline using similar stimulus parameters, and with in vivo control electrodes. The in vitro stimulated electrodes showed evidence of platinum corrosion at high charge density and aggregate charge injection. Significantly, the in vivo stimulated electrodes showed no evidence of stimulus induced corrosion. Indeed, their surfaces were similar to the in vivo control electrodes. In vitro electrochemical studies have demonstrated that proteins play a significant role in the inhibition of platinum dissolution: the present study has demonstrated an inhibitory effect in vivo. This may be due to the presence of proteins.

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This may represent a clear advantage over other materials. Platinum is known to pit and erode with extended use even when used well inside electrochemical limits [31,32] and some forms of iridium oxide have been shown degrade and/or delaminate in particular when the cathodic voltage excursion exceeds −0.6 V [15,33]. In all cases the voltage slopes are close to constant during the majority of the pulse indicating that no Faradaic (water electrolysis) processes are occurring.
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Scanning electron microscopy of chronically stimulated platinum intracochlear electrodes

Abstract

Biomaterials

Biomaterials

Biomaterials

EEG Clin. Neurophysiol.

J. Neurosci. Meth.

Electrical stimulation of the auditory nerve in man

Arch. Otolarngol.

The sensations produced by electrical stimulation of the visual cortex

J. Physiol. Lond.

Electrical stimulation of the conus medullaris in the paraplegic. A 5-year review

Appl. Neurophysiol.

Cerebellar stimulation in man: quantitative changes in spasticity

J. Neurosurg.

Long-term stimulation of the phrenic nerve for diaphragm pacing

A multiple-channel cochlear implant. A summary of results for two patients

Arch. Otolaryngol.

Criteria for selecting electrodes for electrical stimulation: Theoretical and practical considerations

Injury and excitation by electrical currents. A. The balanced pulse pair waveform