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Evaluation of a conducting elastomeric composite material for intramuscular electrode application
X Sally Zheng1, Azante Y Griffith1, Emily Chang2
1Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, United States.
Acta Biomaterialia
|December 22, 2019
Summary
New soft wire electrodes, made from conductive polymers, reduce inflammation and improve muscle stimulation compared to traditional metal electrodes. This biocompatible material also allows for artifact-free medical imaging.
Area of Science:
- Biomaterials Engineering
- Neural Engineering
- Regenerative Medicine
Background:
- Intramuscular electrodes are crucial for muscle stimulation, but metal electrodes cause inflammation and imaging artifacts due to high stiffness.
- Existing metal electrodes have Young's Moduli far exceeding muscle tissue, leading to chronic inflammation and reduced device efficacy.
Purpose of the Study:
- To develop and evaluate a novel intramuscular electrode using a soft, elastomeric conducting polymer composite.
- To compare the biocompatibility, electrical performance, and tissue response of the new soft wire (SW) electrodes against conventional stainless steel (SS) electrodes.
Main Methods:
- Fabrication of SW electrodes from PEDOT-PEG copolymer, silicone, and carbon nanotubes with fluorosilicone insulation.
- In vivo testing of SW and SS electrodes in muscle tissue, assessing electrical impedance, muscle activation thresholds, and tissue response (histology, macrophage phenotyping, AchR clusters).
- Evaluation of imaging compatibility using CT and MR imaging.
Main Results:
- SW electrodes exhibited a Young's modulus mimicking muscle tissue, significantly lower than SS electrodes.
- SW electrodes showed comparable electrical impedance, lower muscle activation thresholds, and stable in vivo performance for 4 weeks.
- Histological analysis revealed reduced fibrotic encapsulation and pro-inflammatory macrophage accumulation around SW electrodes compared to SS electrodes.
- SW implants promoted a shift towards pro-healing macrophages and enhanced acetylcholine receptor (AchR) clustering.
Conclusions:
- The soft, non-metallic SW electrodes demonstrate superior biocompatibility and reduced foreign body response compared to traditional metal electrodes.
- These novel electrodes offer a promising alternative for muscle stimulation applications, enhancing both therapeutic outcomes and diagnostic imaging capabilities.
- The improved electrode-tissue interface achieved with SW electrodes supports healthier muscle function and regeneration.
