Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes

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dc.contributor.authorDalrymple, Ashley
dc.contributor.authorRobles, Ulises
dc.contributor.authorHuynh, Mario
dc.contributor.authorNayagam, Bryony
dc.contributor.authorGreen, Rylie
dc.contributor.authorPoole-Warren, Laura
dc.contributor.authorFallon, James
dc.contributor.authorShepherd, Robert
dc.date.accessioned2020-03-11T04:35:20Z
dc.date.available2020-03-11T04:35:20Z
dc.date.issued2020-03
dc.description.abstractOBJECTIVE: Evaluate electrochemical properties, biological response, and surface characterization of a conductive hydrogel (CH) coating following chronic in vivo stimulation. APPROACH: Coated CH or uncoated smooth platinum (Pt) electrode arrays were implanted into the cochlea of rats and stimulated over a 5 week period with more than 57 million biphasic current pulses. Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured on the bench before and after stimulation, and in vivo during the stimulation program. Electrically-evoked auditory brainstem responses were recorded to monitor neural function. Following explant, the cochleae were examined histologically and electrodes were examined using scanning electron microscopy. MAIN RESULTS: CH coated electrodes demonstrated a bench-top electrochemical advantage over Pt electrodes before and after the electrical stimulation program. In vivo, CH coated electrodes also had a significant advantage over Pt electrodes throughout the stimulation program, exhibiting higher CSC (p = 0.002), larger CIL (p = 0.002), and lower VT impedance (p < 0.001). The CH cohort exhibited a greater tissue response (p = 0.003) with small deposits of particulate material within the tissue capsule. There was no loss in auditory neuron density or change in neural response thresholds in any cochleae. SEM examination of the electrode surface revealed that most CH electrodes exhibited some coating loss; however, there was no evidence of corrosion in the underlying Pt. SIGNIFICANCE: CH coated electrodes demonstrated significant electrochemical advantages on the bench-top and in vivo and maintained neural function despite an increased tissue response and coating loss. While further research is required to understand the cause of the coating loss, CH electrodes provide promise for use in 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., U. A. Aregueta Robles, M. Huynh, B. A. Nayagam, R. Green, L. A. Poole-Warren, J. B. Fallon, and R. K. Shepherd. 2020. Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes. Journal of Neural Engineering: [epub ahead of print].en_US
dc.identifier.issn1741-2552
dc.identifier.urihttp://repository.bionicsinstitute.org:8080/handle/123456789/392
dc.language.isoenen_US
dc.publisherIOP Publishingen_US
dc.subjectElectrical stimulationen_US
dc.subjectNeural prosthesisen_US
dc.subjectElectrochemistryen_US
dc.subjectPlatinumen_US
dc.subjectConductive hydrogelen_US
dc.subjectTissue responseen_US
dc.subjectCochlear implantsen_US
dc.titleElectrochemical and biological performance of chronically stimulated conductive hydrogel electrodesen_US
dc.typeArticleen_US
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