acase@tulane.edu / The application of continuum mechanics principles to biological tissues is paramount to understanding (patho)physiological changes in tissue structure and function. Experimental and mathematical approaches can be utilized to quantify tissue mechanical behavior. In particular, planar biaxial mechanical testing of soft tissues (i.e. applying loads or deformation along two axes in the same plane) has proven to mimic physiologically relevant conditions for most soft tissues. Constitutive relations can then be formulated based on biaxial data to describe and predict soft tissue mechanical behavior. These mathematical tools could aid in delineating underlying mechanisms of and evaluating treatments for various clinically relevant issues. Therefore, the overall objective of this thesis is to build a custom planar biaxial mechanical testing device to characterize the mechanical properties of soft biological tissues to identify appropriate constitutive relations. A custom planar biaxial mechanical testing device was successfully built and validated. A LabVIEW program was written to interface with the stepper motors and load cells of the device to control their movements. A mechanical testing protocol was developed and incorporated to enable the characterization of a variety of soft tissue structure-function relationships. Foundations were laid for studies using the planar biaxial device for research in a tissue-engineered nipple-areolar complex (NAC), pelvic floor disorders, and age-specific tendinopathy. The planar biaxial device has the potential to impact many areas of clinical research. / 1 / Taylor McCrady

acase@tulane.edu / Soft tissue mechanics attempts to describe biological tissues such as skin, tendon, and the reproductive organs using concepts found in mechanical engineering. By approaching soft tissues using this framework, the complex biomechanical response of such tissues, which have been implicated in the development of disease and injury, can be ascertained and quantified. Robust mechanical tests, in which tissue stress-strain behavior is characterized, are needed in order to inform constitutive models of healthy and diseased tissue. The overall objective of this thesis was to design, construct, program, and validate a planar biaxial device capable of testing soft tissues. Improvements and redesigns were made to the device to better suit the nature of testing required for soft tissue. Custom grips, modules, and software were developed and fabricated to facilitate accurate biaxial mechanical tests. Optimized for testing of small soft tissues, the biaxial device is an evolution of the standard approach towards mechanical testing. The overall device and the individual systems were validated internally and externally. Pilot studies were conducted on murine skin, compared to existing data from literature, and observed to correspond with known stress-strain and load-displacement properties. Further, experimental protocols were developed to evaluate the biaxial behavior of soft tissues, including cervical, uterine, vaginal, and uterosacral ligament tissue. Studies were described in which experimental data could be used to establish structure-function relationships describing reproductive tissue. Results from these studies could be used to elucidate the underlying mechanical etiologies of preterm birth and pelvic organ prolapse. / 1 / Jonathan Nguyen