26dga190 10.3205/26dga190 urn:nbn:de:0183-26dga1904 Meeting Abstract Bhavsar Bhavsar Mit Balvantray MB

HNO Klinik/Medizinische Hochschule Hannover, Hannover, Deutschland

author Sehlmeyer Sehlmeyer Merle M

Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Hannover, Deutschland

author Roger Roger Yvonne Y

Clinic for Orthopedic Surgery, Hannover Medical School, Hannover, Deutschland

author Hoffmann Hoffmann Andrea A

Clinic for Orthopedic Surgery, Hannover Medical School, Hannover, Deutschland

author Kral Kral Andrej A

HNO Klinik/Medizinische Hochschule Hannover, Hannover, Deutschland

author Prenzler Prenzler Nils N

HNO Klinik/Medizinische Hochschule Hannover, Hannover, Deutschland

author Zimmermann Zimmermann Stefan S

Leibniz University Hannover, Institute of Electrical Engineering and Measurement Technology, Hannover, Deutschland

author Maier Maier Hannes H

HNO Klinik/Medizinische Hochschule Hannover, Hannover, Deutschland

author German Medical Science GMS Publishing House

Düsseldorf

610 20260302 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0642 190 Deutsche Gesellschaft für Audiologie e. V. 28. Jahrestagung der Deutschen Gesellschaft für Audiologie Postersession Oldenburg 20260304 20260306 190 TextCochlear implants (CIs) have proven to be highly effective neural prostheses, widely used to restore hearing in individuals with sensorineural hearing loss. However, following implantation, CIs can trigger an immune response that leads to cell layer formation (fibrosis) in the cochlea causing low stimulation efficiency and suboptimal clinical outcomes. Electrochemical Impedance Spectroscopy (EIS) offers a powerful method for assessing the functionality of CI both during and after surgery. However, it‘s full potential, particularly in analyzing the electrical properties of CIs, detecting the cell layer by distinguishing between different cell types, remains unutilized. This study aims to develop and validate an equivalent electrical circuit (EEC) model that accurately represents the electrical properties of CI arrays and can reliably detect formation of cell layer on CI electrode arrays. The study involves four CI electrode arrays from different manufacturers (MED-EL, Advanced Bionics, Oticon, and Cochlear). Impedance measurements were conducted using an HP4192A impedance analyzer in a frequency range from 5 Hz to 13 MHz. The electrical equivalent circuit (EEC) of the CI electrodes was modelled, involving linear elements, as well as the electrode-electrolyte interface, using two non-linear bilayer models (Cole-Cole and Schwan-Faraday). A layer of human mesenchymal stromal cells (MSCs) was developed on the CI electrodes and impedance measurements were conducted to analyze changes in the impedance and its sensitivity and specificity. A general nonlinear electric element circuit model applicable to all types of CIs was derived that allows the determination of local impedances between neighboring CI array electrodes with an accuracy of < 10%. Our cell layer experiments demonstrated a clear increase in impedance across the frequency range when a layer of cells was present on the CI electrode. This increase was reversed after enzymatic cleaning, confirming that the observed impedance changes were due to the cell layer. These findings validate the use of impedance spectroscopy for detecting biological layers on cochlear implant electrodes. In conclusion, our study developed and validated an EEC model to describe the electrical properties of CI electrode arrays along with its ability to detect presence of cell layer on CI electrodes using precision impedance spectroscopy. Our findings underscore the potential of modelling and identifying the coverage of electrodes with biological material using impedance spectroscopy. Sehlmeyer M Bhavsar MB Zimmermann S Maier H A simple electrical circuit model for impedance spectroscopy with cochlear implant electrodes 2024 Hear Res 109125 Sehlmeyer M, Bhavsar MB, Zimmermann S, Maier H. A simple electrical circuit model for impedance spectroscopy with cochlear implant electrodes. Hear Res. 2024 Nov;453:109125. DOI: 10.1016/j.heares.2024.109125 http://dx.doi.org/10.1016/j.heares.2024.109125 Sehlmeyer M Makarenko M Schoerner N Bhavsar MB Blank T Maier HJ Kral A Maier H Zimmermann S Electrical equivalent circuit for analyzing the effect of signal shape on power distribution in cochlear implant electrodes and surrounding tissue 2025 Sci Rep 20136 Sehlmeyer M, Makarenko M, Schoerner N, Bhavsar MB, Blank T, Maier HJ, Kral A, Maier H, Zimmermann S. Electrical equivalent circuit for analyzing the effect of signal shape on power distribution in cochlear implant electrodes and surrounding tissue. Sci Rep. 2025 Jun 20;15(1):20136. DOI: 10.1038/s41598-025-04840-5 http://dx.doi.org/10.1038/s41598-025-04840-5 0 0 0 0