146 - Material characterization of thermoplastic polyurethanes (TPU) and elastomers (TPE) for development of 3D-Printed surrogate organs for medical training

Poster Board Number: 146
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Odd poster #s – first hour
Even poster #s – second hour

Co-authors:

Anatasia Lucci - Dept of Mechanical, Materials, and Aerospace Engineering - West Virginia University; Bruce Palmer - Dept of Pathology, Anatomy, and Laboratory Medicine - West Virginia University; Eduardo Sosa - Professor, Dept of Mechanical, Materials, and Aerospace Engineering, West Virginia University

Abstract Body :
Introduction and ObjectiveCadaveric specimens are a necessary but limited resource for training medical students on basic surgical skills. The availability of accessible additive manufacturing technology and flexible thermoplastic materials provides a viable avenue for developing surrogate 3D-printed organs that can provide access to training specimens. These surrogate specimens could reduce the need for cadaveric specimens or, at a minimum, provide students the opportunity to practice with 3D-printed surrogates before transitioning to those specimens. This research aims to determine which thermoplastic material most closely mimics mechanical properties such as the hardness and stiffness of human organs and allows 3D printing surrogate organs to be used as a safe educational tool.Materials and MethodsA set of soft materials (Shore hardness ranging from 75A to 95A) such as thermoplastic polyurethanes (TPU) and elastomers (TPE) are selected as candidate materials for 3D printing of surrogate organs using a fusion deposition modeling (FDM) printer. The mechanical properties of these materials are determined by a series of hardness, puncture, and cutting tests conducted for different printing configurations and testing conditions. Test results determined the most suitable material for 3D printing surrogate organs. Test results are compared to values obtained from unfixed and fixed cadaveric organs, porcine tissue, and related previous data reported in the literature. Professional anatomists and pathologists also assessed a prototype model manufactured with the selected material to determine the level of realism and practicality of the 3D-printed prototype.ResultsMechanical test results indicated that candidate materials were stiffer than tissue material properties reported in the literature and measurements on pork tissues. Despite this limitation, the material that exhibited the lowest required cutting force was deemed the best for this study. The scalpel cutting and the scalpel puncture tests were the two most essential tests in determining the force needed to make an incision. A combination of 15% infill with one of the softer materials (75A) can produce a mechanical behavior comparable to actual organs. Cutting tests conducted by a group of five anatomists indicated that the best infill percentage for the final surrogate organ was 15% to 20%.Conclusions and SignificanceMechanical test results allowed the selection of suitable printing materials, and overall feedback from anatomists indicated that the synthetic models are helpful as a teaching tool to educate medical students. However, additional tests on softer materials are needed to approximate the stiffness and cuttability of surrogate specimens better while maintaining the safety of the users.