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A COMPARATIVE ANALYSIS OF LOCAL AND GLOBAL PERIPHERAL NERVE MECHANICAL PROPERTIES DURING CYCLICAL TENSILE TESTING

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thesis
posted on 2022-07-12, 18:19 authored by Onna Marie DoeringOnna Marie Doering

  

Understanding the mechanical properties of peripheral nerves is essential for chronically implanted device design. The work in this thesis aimed to understand the relationship between local deformation responses to global strain changes in peripheral nerves. A custom-built mechanical testing rig and sample holder enabled an improved cyclical uniaxial tensile testing environment on rabbit sciatic nerves (N=5). A speckle was placed on the surface of the nerve and recorded with a microscope camera to track local deformations. The development of a semi-automated digital image processing algorithm systematically measured local speckle dimension and nerve diameter changes. Combined with the measured force response, local and global strain values constructed a stress-strain relationship and corresponding elastic modulus. Preliminary exploration of models such as Fung and 2-Term Mooney-Rivlin confirmed the hyperelastic nature of the nerve. The results of strain analysis show that, on average, local strain levels were approximately five times smaller than globally measured strains; however, the relationship was dependent on global strain magnitude. Elastic modulus values corresponding to ~9% global strains were 2.070 ± 1.020 MPa globally and 10.15 ± 4 MPa locally. Elastic modulus values corresponding to ~6% global strains were 0.173 ± 0.091 MPa globally and 1.030 ± 0.532 MPa locally.   

Funding

Reversible block of nerve conduction using low frequency alternating currents

National Institute of Biomedical Imaging and Bioengineering

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History

Degree Type

  • Master of Science

Department

  • Biomedical Engineering

Campus location

  • Indianapolis

Advisor/Supervisor/Committee Chair

Ken Yoshida

Additional Committee Member 2

Joseph Wallace

Additional Committee Member 3

Adam Goodwill