Electrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo study

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dc.contributor.authorDalrymple, Ashley
dc.contributor.authorHuynh, Mario
dc.contributor.authorNayagam, Bryony
dc.contributor.authorLee, Curtis
dc.contributor.authorWeiland, Greg
dc.contributor.authorPetrossians, Artin
dc.contributor.authorWhalen, John
dc.contributor.authorFallon, James
dc.contributor.authorShepherd, Robert
dc.date.accessioned2020-05-25T04:32:51Z
dc.date.available2020-05-25T04:32:51Z
dc.date.issued2020-05
dc.description.abstractOBJECTIVE: To evaluate the electrochemical properties, biological response, and surface characterization of an electrodeposited Platinum-Iridium (Pt-Ir) electrode coating on cochlear implants subjected to chronic stimulation in vivo. APPROACH: Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured bench-top before and after implant and in vivo. Coated Pt-Ir and uncoated Pt electrode arrays were implanted into cochlea of normal hearing rats and stimulated for ~4 hours/day, 5 days/week for 5 weeks. Neural function was monitored using electrically-evoked auditory brainstem responses. After explant, the electrode surfaces were assessed, and cochleae examined histologically. MAIN RESULTS: When measured on bench-top before and after stimulation, Pt-Ir coated electrodes had significantly lower VT impedance (p < 0.001) and significantly higher CSC (p < 0.001) and CIL (p < 0.001) compared to uncoated Pt electrodes. In vivo, the CSC and CIL of Pt-Ir were significantly higher than Pt throughout the implantation period (p = 0.047 and p < 0.001, respectively); however, the VT impedance (p = 0.3) was not. There was no difference in foreign body response between material cohorts, although cochleae implanted with coated electrodes contained small deposits of Pt-Ir. There was no evidence of increased neural loss or loss of neural function in either group. Surface examination revealed no Pt corrosion on any electrodes. SIGNIFICANCE: Electrodeposited Pt-Ir electrodes demonstrated significant improvements in electrochemical performance on the bench-top and in vivo compared to uncoated Pt. Neural function and tissue response to Pt-Ir electrodes were not different from uncoated Pt, despite small deposits of Pt-Ir in the tissue capsule. Electrodeposited Pt-Ir coatings offer promise as an improved electrode coating for active neural prostheses.en_US
dc.description.sponsorshipThis work was funded by the NHMRC of the Australian Government (APP1122055) and the Garnett Passe and Rodney Williams Memorial Foundation for which we are most grateful. The Bionics Institute acknowledges support of the Victorian Government through Operational Infrastructure Support Program.en_US
dc.identifier.citationDalrymple, A. N., M. Huynh, B. A. Nayagam, C. Lee, G. R. Weiland, A. Petrossians, J. J. Whalen Iii, J. B. Fallon, and R. K. Shepherd. 2020. Electrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo study. Journal of Neural Engineering: [epub ahead of print].en_US
dc.identifier.issn1741-2552
dc.identifier.urihttp://repository.bionicsinstitute.org:8080/handle/123456789/398
dc.language.isoenen_US
dc.publisherIOP Publishingen_US
dc.subjectElectrical stimulationen_US
dc.subjectNeural prosthesisen_US
dc.subjectElectrochemistryen_US
dc.subjectPlatinumen_US
dc.subjectElectrodeposited Pt-Iren_US
dc.subjectTissue responseen_US
dc.subjectCochlear implantsen_US
dc.subjectElectrode impendanceen_US
dc.subjectElectrode neural interfaceen_US
dc.titleElectrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo studyen_US
dc.typeArticleen_US
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