Malik, Faizan2023-11-282023-11-282023-07https://hdl.handle.net/11299/258591University of Minnesota M.S.M.E. thesis. July 2023. Major: Mechanical Engineering. Advisor: Timothy Kowalewski. 1 computer file (PDF); vii, 70 pages.Physical and virtual medical simulators are increasingly necessary in order to facilitate medical training; however, accurate medical simulators rely on appropriately characterized tissues. It can often be difficult to characterize living (in vivo) tissue, due to ethical and physical constraints. Thus, the vast majority of collected tissue data comes from from preserved, cadaveric tissue, which is known to differ from living tissue in mechanical response. The focus of my thesis has been to quantify the differences, if any, in the mechanical responses of tissue from in vivo to preserved tissue, and various states in between. This was done by gathering data from porcine liver and peritoneal (belly) tissues using a handheld grasper device that recorded force and displacement data of the tissue during a grasp. The tissues were tested under five different tissue states: in vivo, post mortem, ex vivo (tissues extracted from carcass), post-refrigeration, and post-freeze. Tissue data was collected from n = 5 animals, and then the data was processed to obtain a derived ``stiffness" value for each grasp. Finally, a statistical comparison of these stiffnesses reveal that there is no statistically significant change in tissue stiffness for the tested tissues from the in vivo to the post-freeze states, thus supporting the use of preserved tissue to derive mechanical properties. We observed that the variability in tissue stiffnesses between the in-vivo and post-freeze states was comparable to the variability between patients. However, there are many limitations to this conclusion, and we did determine some statistically significant increases in tissue stiffness during the intermediate post mortem, ex vivo, and post refrigeration states.enmedical simulatorsmedical trainingtissue characterizationThesis or Dissertation