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In vitro evaluation of the long-term stability of polyimide as a material for neural implants

Paper ID Volume ID Publish Year Pages File Format Full-Text
9696 643 2010 10 PDF Available
Title
In vitro evaluation of the long-term stability of polyimide as a material for neural implants
Abstract

In order to be used as a material for neural prostheses, polyimide has to withstand the body environment over years. To obtain more information about the long-term stability of this material, we tested three commercially available polyimides (PI2611 – HD-Microsystems (type: BPDA-PPD), U-Varnish-S – UBE (type: BPDA-PPD), Durimide 7510 – Fujifilm (type: information not provided)). Specimens were stored in phosphate buffered saline (PBS) at 37 °C to simulate body temperature and at elevated temperatures of 60 °C and 85 °C to accelerate aging. During the course of 20 months, stress-strain curves were measured monthly by tensile testing. From these curves the Young's modulus, the stress and strain at break, the stress at 10% strain as well as the fracture energy were extracted and used to characterize and to statistically evaluate the mechanical material properties. Mass loss was determined by weighing polyimide foils (Upilex25S - UBE) and optical measurements were conducted to examine changes in chemical structure and crystallinity. At 37 °C and 60 °C no change in material behavior could be observed, except for an increase of the Young's modulus of the BPDA-PPD type stored at 60 °C. This demonstrates the long-term stability of all tested polyimides with respect to PBS. All extracted quantities mentioned above, as well as the mass, decreased in specimens stored in PBS at 85 °C. As a comparison, BPDA-PPD type specimens stored at 85 °C in deionized water showed no change in any property but behaved similarly to the reference material.

Keywords
Neural prostheses; Polyimide degradation; Accelerated aging; Mechanical properties; Phosphate buffered saline
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In vitro evaluation of the long-term stability of polyimide as a material for neural implants
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 31, Issue 13, May 2010, Pages 3449–3458
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us