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Integration of Polarized Spatial Frequency Domain Imaging (pSFDI) with a Biaxial Mechanical Testing System for Dynamic Quantification of Collagen Architecture in Soft Collagenous Tissues

51 Pages Posted: 25 Jul 2019 First Look: Accepted

See all articles by Samuel Jett

Samuel Jett

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Luke Hudson

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Ryan Baumwart

Oklahoma State University - Stillwater - Center for Veterinary Health Sciences

Bradley N. Bohnstedt

University of Oklahoma - Department of Neurosurgery

Arshid Mir

University of Oklahoma - Division of Pediatric Cardiology

Harold M. Burkhart

University of Oklahoma - Division of Cardiothoracic Surgery

Gerhard A. Holzapfel

Graz University of Technology - Institute of Biomechanics; Norwegian University of Science and Technology (NTNU) - Department of Structural Engineering

Chung-Hao Lee

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory; University of Oklahoma - Institute for Biomedical Engineering, Science and Technology

Yi Wu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

Abstract

Collagen fiber networks provide the structural strength of tissues such as tendons, skin, and arteries. Quantifying the response of the fiber architecture to mechanical loads is essential towards a better understanding of the tissue-level mechanical behaviors, especially in assessing disease-driven functional changes. To enable novel investigations into these dynamic fiber structures, a polarized spatial frequency domain imaging (pSFDI) device was developed and, for the first time, integrated with a biaxial mechanical testing system. The integrated instrument is capable of a wide-field and dynamic quantification of the fiber orientation and degree of optical anisotropy (DOA), representing the local strength of fiber alignment. The performance of this integrated instrument was assessed through uniaxial testing on tendon tissues with known collagen fiber microstructures. Our results revealed that the fiber orientation of the tendon tissue changed indiscernibly, whereas the fibers became better aligned with the average DOA increasing from 0.126 to 0.215 under 0% and 3% uniaxial strains, respectively. The integrated instrument was further applied to study the mitral valve anterior leaflet (MVAL) tissue subjected to various biaxial loadings. The fiber orientations within the MVAL demonstrated a proclivity towards the tissue's circumferential direction under all loading protocols, while certain fiber groups re-oriented towards the tissue's radial direction under radially-dominant loading. Our results also showed that fibers were generally better aligned under equibiaxial (DOA=0.088) and circumferentially-dominant loading (DOA=0.084) than under the radially-dominant loading (DOA=0.074), indicating circumferential predisposition. These novel findings exemplify a deeper understanding of dynamic collagen fiber microstructures obtained through the integrated opto-mechanical instrument.

Keywords: collagen fiber architecture, biaxial loading, microstructure, quantitative optical technique, polarization imaging, heart valve

Suggested Citation

Jett, Samuel and Hudson, Luke and Baumwart, Ryan and Bohnstedt, Bradley N. and Mir, Arshid and Burkhart, Harold M. and Holzapfel, Gerhard A. and Lee, Chung-Hao and Wu, Yi, Integration of Polarized Spatial Frequency Domain Imaging (pSFDI) with a Biaxial Mechanical Testing System for Dynamic Quantification of Collagen Architecture in Soft Collagenous Tissues (2019). Available at SSRN: https://ssrn.com/abstract=3425374 or http://dx.doi.org/10.2139/ssrn.3425374

Samuel Jett

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Luke Hudson

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

Ryan Baumwart

Oklahoma State University - Stillwater - Center for Veterinary Health Sciences

208 S. McFarland Street
Stillwater, OK 74078
United States

Bradley N. Bohnstedt

University of Oklahoma - Department of Neurosurgery

Oklahoma City, OK 73104
United States

Arshid Mir

University of Oklahoma - Division of Pediatric Cardiology

OK
United States

Harold M. Burkhart

University of Oklahoma - Division of Cardiothoracic Surgery

OK
United States

Gerhard A. Holzapfel

Graz University of Technology - Institute of Biomechanics

Kopernikusgasse 24/IV
Graz, Styria A-8010
Austria

Norwegian University of Science and Technology (NTNU) - Department of Structural Engineering

Trondheim NO-7491
Norway

Chung-Hao Lee (Contact Author)

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory ( email )

307 W Brooks
Norman, OK 73019
United States

University of Oklahoma - Institute for Biomedical Engineering, Science and Technology ( email )

307 W Brooks
Norman, OK 73019
United States

Yi Wu

University of Oklahoma - Biomechanics and Biomaterials Design Laboratory

307 W Brooks
Norman, OK 73019
United States

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