Design and Validation of a Dynamic Pressure-Based Loading Device and 3D Strain Tracking Protocol for Ventral Hernia Modeling

It is estimated that 350,000-500,000 ventral hernia repair surgeries are performed each year in the United States. While the long-term recurrence rate of ventral hernia repairs is not yet known, when tissues are exposed to the trauma of surgery, there is always the chance of recurrence. Commonly used ex vivo testing methods for determining the mechanical properties of the abdominal wall and biomaterials for hernia repair consist primarily of uniaxial and biaxial testing, which are not physiologically relevant loading environments. The need for a testing device that can exert physiologically relevant loads ex vivo to an abdominal wall is crucial for the development of more effective repair strategies and products. After abdominal hernia repairs, coughing poses a major threat to the structural integrity of the repair site. During a cough, the intra-abdominal pressure (IAP) can rise as high as 2.5 psi, compared to the normal IAP of approximately 0.1-0.2 psi. The goal of this project was to design a testing device that can apply and measure a representative coughing force applied to an ex vivo porcine abdominal wall, and develop a strain tracking protocol to track three-dimensional abdominal deformation throughout the duration of the cough. The constructed device was successful in applying a physiologically relevant force to a porcine abdominal wall, and subsequently decreasing the force back to a normal IAP in less than 2 seconds. The maximum force of the cough can be easily controlled using the Arduino controller, which makes the device robust enough to explore the effects of a range of pressures. By recording a video of the cough using a 3D camera, we were able to successfully track the deformation of the tissue in three-dimensions with an acceptable level of accuracy. The design and validation of this testing method will pave the way for a variety of experiments that will provide greater insight into the mechanical behavior of the abdominal wall and the effectiveness of various repair strategies and products on restoring native tissue function

Design and Use of a Bilateral Grip Strength Device for Assessing Forelimb Function in Rodents

From the Washington University Office of Undergraduate Research Digest (WUURD), Vol. 13, 05-01-2018. Published by the Office of Undergraduate Research. Joy Zalis Kiefer, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Lindsey Paunovich, Editor; Helen Human, Programs Manager and Assistant Dean in the College of Arts and Sciences Mentor(s): Spencer Lak

Musculoskeletal Soft Tissue Laboratory Spring 2018 Kivitz Progress Report

This is a semester progress report for the spring 2018 semester working in the Musculoskeletal Soft Tissue Laboratory under the direction of Dr. Spencer Lake. I had two primary tasks/projects I was working on this semester. In chronological order, I was helping Alex Reiter with the editing of gait analysis images to rectify the noise and any problems with the initial code that may have had an impact on the filtering process. After that, I began designing an in vivo range of motion mechanical testing device for unilaterally injured rodents

Activity Monitoring System

This semester I constructed an activity monitoring arena and determined the appropriate data acquisition settings. Videos are recorded and processed at 30 frames per seconds and a “minimum distance travelled filter” is used to eliminate any motion that does not require the animal to take a step. The filter does capture any movements that do require a step, so we will be able to determine an average degree of activity during the animal’s session of free cage activity

Redesigning a Bilateral Grip Strength Device for Assessing Forelimb Function in Rodents

My primary complete accomplishment of the Fall 2017 semester in the Musculoskeletal Soft Tissue Laboratory is the addition of 3 3D printed parts to the grip strength device to improve the precision of the device. To reach the end result of these 3 parts, I 3D-modelled the parts, 3D printed the prototypes, and integrated the parts into the device for testing. Near the end of the semester I had seen this process through, and the grip strength device is now fully functional and the most accurate and precise it has been. Aside from my primary project of the grip strength device, Alex Reiter and I reconstructed AGATHA with thicker acrylic

Universal Tube Fixture

The goal of this design project was to create a device that can aid in the assembly of glue joints between concentric tubes. In many medical devices, whether they be laser probes, retractable injectors, or other devices with actuating parts, there are often concentric glue joints. The problem we are trying to solve is controlling where the 2 tubes are relative to one another when they are glued