Development of a two dimensional optical fiber force transducer for constitutive modeling of soft tissue

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaf 101).Issued also on microfiche from Lange Micrographics.Constitutive modeling of soft tissue has provided better understanding of their function and behavior in both normal and pathophysiological conditions. The ability to predict growth and remodeling of the tissue under the influence of applied mechanical loads suggests novel treatment methods for diseases like atherosclerosis, cardiac ischema, aneurysms, congestive heart failure and many others. Material properties such as anisotropy, nonlinearity, inhomogenity, and viscoelasticity make it difficult to characterize soft tissue. Biaxial testing (first suggested by Revlin) is an important tool to analyze nonlinear materials and biaxial testing devices have been widely used by bioengineers to develop constitutive models of soft tissue. The most broadly used model is that suggested by Y. C. Fung. Although a useful instrument, conventional biaxial testing devices suffer from certain limitations such as the inability to test small sized specimens, gripping techniques and its effects on behavior of tissue under biaxial loading state. Also the device cannot be used to perform shear tests on tissue and hence cannot be effectively used to model behavior of tissues like endocardium and myocardium that undergo large shear deformations under normal physiological conditions. The two-dimensional optical fiber force transducer aims at overcoming some of these limitations. Since the transducer can measure both axial and shear forces it can be used in fabricating devices capable of shear testing. Also the small size optical fibers make the transducers suitable to be used in instruments for testing small specimens. This work presents a theoretical design of such a transducer, its fabrication and calibration procedure, and its testing for accuracy and sensitivity