Cargando…
Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes
Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to fals...
Autores principales: | , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2018
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266965/ https://www.ncbi.nlm.nih.gov/pubmed/30424513 http://dx.doi.org/10.3390/mi9110587 |
_version_ | 1783375957818605568 |
---|---|
author | Straka, Malgorzata M. Shafer, Benjamin Vasudevan, Srikanth Welle, Cristin Rieth, Loren |
author_facet | Straka, Malgorzata M. Shafer, Benjamin Vasudevan, Srikanth Welle, Cristin Rieth, Loren |
author_sort | Straka, Malgorzata M. |
collection | PubMed |
description | Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to false positives. We implanted cohorts of five iridium oxide (IrOx) and six platinum (Pt) Utah arrays into the sciatic nerve of rats, and collected the electrochemical impedance spectroscopy (EIS) up to 12 weeks or until array failure. We developed a method to classify the shapes of the magnitude and phase spectra, and correlated the classifications to circuit models and electrochemical processes at the interface likely responsible. We found categories of EIS characteristic of iridium oxide tip metallization, platinum tip metallization, tip metal degradation, encapsulation degradation, and wire breakage in the lead. We also fitted the impedance spectra as features to a fine-Gaussian support vector machine (SVM) algorithm for both IrOx and Pt tipped arrays, with a prediction accuracy for categories of 95% and 99%, respectively. Together, this suggests that these simple and computationally efficient algorithms are sufficient to explain the majority of variance across a wide range of EIS data describing Utah arrays. These categories were assessed over time, providing insights into the degradation and failure mechanisms for both the electrode–tissue interface and wire bundle. Methods developed in this study will allow for a better understanding of how EIS can characterize the physical changes to electrodes in vivo. |
format | Online Article Text |
id | pubmed-6266965 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-62669652018-12-06 Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes Straka, Malgorzata M. Shafer, Benjamin Vasudevan, Srikanth Welle, Cristin Rieth, Loren Micromachines (Basel) Article Characterizing the aging processes of electrodes in vivo is essential in order to elucidate the changes of the electrode–tissue interface and the device. However, commonly used impedance measurements at 1 kHz are insufficient for determining electrode viability, with measurements being prone to false positives. We implanted cohorts of five iridium oxide (IrOx) and six platinum (Pt) Utah arrays into the sciatic nerve of rats, and collected the electrochemical impedance spectroscopy (EIS) up to 12 weeks or until array failure. We developed a method to classify the shapes of the magnitude and phase spectra, and correlated the classifications to circuit models and electrochemical processes at the interface likely responsible. We found categories of EIS characteristic of iridium oxide tip metallization, platinum tip metallization, tip metal degradation, encapsulation degradation, and wire breakage in the lead. We also fitted the impedance spectra as features to a fine-Gaussian support vector machine (SVM) algorithm for both IrOx and Pt tipped arrays, with a prediction accuracy for categories of 95% and 99%, respectively. Together, this suggests that these simple and computationally efficient algorithms are sufficient to explain the majority of variance across a wide range of EIS data describing Utah arrays. These categories were assessed over time, providing insights into the degradation and failure mechanisms for both the electrode–tissue interface and wire bundle. Methods developed in this study will allow for a better understanding of how EIS can characterize the physical changes to electrodes in vivo. MDPI 2018-11-12 /pmc/articles/PMC6266965/ /pubmed/30424513 http://dx.doi.org/10.3390/mi9110587 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Straka, Malgorzata M. Shafer, Benjamin Vasudevan, Srikanth Welle, Cristin Rieth, Loren Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title | Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title_full | Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title_fullStr | Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title_full_unstemmed | Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title_short | Characterizing Longitudinal Changes in the Impedance Spectra of In-Vivo Peripheral Nerve Electrodes |
title_sort | characterizing longitudinal changes in the impedance spectra of in-vivo peripheral nerve electrodes |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266965/ https://www.ncbi.nlm.nih.gov/pubmed/30424513 http://dx.doi.org/10.3390/mi9110587 |
work_keys_str_mv | AT strakamalgorzatam characterizinglongitudinalchangesintheimpedancespectraofinvivoperipheralnerveelectrodes AT shaferbenjamin characterizinglongitudinalchangesintheimpedancespectraofinvivoperipheralnerveelectrodes AT vasudevansrikanth characterizinglongitudinalchangesintheimpedancespectraofinvivoperipheralnerveelectrodes AT wellecristin characterizinglongitudinalchangesintheimpedancespectraofinvivoperipheralnerveelectrodes AT riethloren characterizinglongitudinalchangesintheimpedancespectraofinvivoperipheralnerveelectrodes |