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Published on: September 27, 2013
Long-term usability and bio-integration of polyimide-based intra-neural stimulating electrodes
S Wurth1, M Capogrosso2, S Raspopovic2
1Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Polyimide intra-neural electrodes show stable function and biocompatibility for over six months in rat sciatic nerves. This research supports long-term clinical applications for restoring sensation and motor function.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Materials Science
Background:
- Intra-neural implants offer potential for restoring sensation and motor function.
- Long-term usability and bio-integration of these implants require further characterization for clinical translation.
Purpose of the Study:
- To longitudinally assess the selectivity, stability, functionality, and biocompatibility of polyimide-based intra-neural implants.
- To investigate the foreign body response and its impact on implant performance over six months.
Main Methods:
- Implantation of polyimide intra-neural electrodes into the sciatic nerve of 23 rats for up to six months.
- Longitudinal assessment of electrode stimulation threshold, impedance, and selectivity.
- Histological analysis of implant encapsulation, nerve tissue, and foreign body response.
- Evaluation of motor function before and after implant removal.
Main Results:
- Electrode stimulation threshold and impedance moderately increased in the first four weeks, then stabilized.
- A fibrotic capsule formed around implants, correlating with electrical property changes.
- Stable electrode selectivity allowed precise control of ankle muscles.
- Foreign body response evolved, with initial macrophage infiltration followed by giant cell formation, without affecting nerve fiber density.
- No significant alteration in skilled leg movements was observed after implant removal.
Conclusions:
- Polyimide-based intra-neural implants demonstrate functional stability and biocompatibility for over six months.
- The study characterizes the interplay between foreign body response and electrical properties of active electrodes.
- Findings support the realistic pathway for long-term clinical applications of intra-neural electrodes.
