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Biomed Microdevices. 2016 Oct;18(5):81. doi: 10.1007/s10544-016-0106-7.

Intracortical polyimide electrodes with a bioresorbable coating.

Author information

1
Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 102, 79110, Freiburg, Germany. hassler@imtek.de.
2
Bernstein Center Freiburg, Hansastr. 9a, 79104, Freiburg, Germany. hassler@imtek.de.
3
Bernstein Center Freiburg, Hansastr. 9a, 79104, Freiburg, Germany.
4
Institute for Neuroanatomy, Center for Anatomy, University of Goettingen, Kreuzbergring 36, 37075, Goettingen, Germany.
5
Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 102, 79110, Freiburg, Germany.
6
Department of Neurosurgery, University Medical Center Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany.
7
Brainlinks-BrainTools, Research Cluster of Excellence (EXC 1086), University of Freiburg, Freiburg, Germany.

Abstract

Polyimide based shaft electrodes were coated with a bioresorbable layer to stiffen them for intracortical insertion and to reduce the mechanical mismatch between the target tissue and the implanted device after degradation of the coating. Molten saccharose was used as coating material. In a proof-of-concept study, the electrodes were implanted into the cortex of Wistar rats and the insertion forces during implantation were recorded. Electrochemical impedance spectroscopy was performed immediately after implantation and up to 13 weeks after implantation to monitor the tissue response to the implanted electrodes. The recorded spectra were modeled with an equivalent circuit to differentiate the influence of the single components. In one rat, a peak in the encapsulation resistance was observable after two weeks of implantation, indicating the peak of the acute inflammatory response. In another rat, the lowest resistances were observed after four weeks, indicating the termination of the acute inflammatory response. Multiunit activity was recorded with an adequate signal to noise ratio to allow spike sorting. Histology was performed after 7, 45 and 201 days of implantation. The results showed the highest tissue reaction after 45 days and confirmed impedance data that acute inflammatory reactions terminate over time.

KEYWORDS:

Bioresorbable; Coating; Electrode; Intracortical; Polyimide

PMID:
27534649
DOI:
10.1007/s10544-016-0106-7
[Indexed for MEDLINE]

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