PolyJet 3D Printing of Tissue Mimicking Materials: An Investigation of Characteristic Properties of 3D Printed Synthetic Tissue

Abstract

Current anatomical 3D printing has been primarily used for education, training, and surgical planning purposes. This is largely due to the models being printed in materials which excel at replicating macro-level organic geometries; however, these materials have the drawback of unrealistic mechanical behavior and system properties compared to biological tissue. The new Digital Anatomy (DA) family of materials from Stratasys utilizes composite printed materials to more closely mimic mechanical behavior of biological tissue, potentially allowing more realistic models for design evaluation. Various experimental DA Solid Organ (SO) configurations were quantitatively evaluated under axial loading for comparison with porcine liver in terms of stiffness. Additionally, Structural Heart - Myocardium (Myo) configurations were quantitatively evaluated under different lubricant conditions for comparison with porcine epicardium and aorta in terms of lubricity. Finally, experimental DA Subcutaneous Tissue configurations were qualitatively evaluated by experts with significant pre-clinical implant experience for cutting, tunneling, and puncture procedures.In general, the experimental SO configurations showed promising compliance results when compared to porcine liver. The stiffness of DA configurations was either within the same range or on the lower bound of porcine tissue stiffness values. The lubricity of DA configurations with surface treatments was comparable with porcine epicardium and aorta. In terms of qualitative cutting, DA did not perform well for any of the configurations; however, tunneling and puncture were rated favorably for some of the experimental configurations. Despite some limitations, DA feels closer to real tissue than other commercially available 3D printed materials. Furthermore, the lower sample-to-sample variability of DA allows for repeatability not provided by biological tissue. The promising results and repeatability indicate that DA materials can be used to configure structures with similar characteristic mechanical properties to porcine liver, epicardium, and subcutaneous tissue, adding new value as not only an educational, training, and surgical tool, but also as a research tool.

State-of-the-art silicone molded models for simulation of arterial switch operation: Innovation with parting-and-assembly strategy

“… 6 , 7 , 8 , 9 , 10 , 11 Although they have been well received by users, the 3D printed models produced with the currently available technology do not have the optimal physical properties for traction, cutting, and suturing during simulation. 6 , 9 , 10 , 12 , 13 , 14 , 15 To overcome the weaknesses of the 3D printed models, silicone molded models of TGA for ASO were successfully introduced at the 2020 Annual HOST course. The major breakthrough in silicone molding in this study was the “parting and assembly” strategy, in which the separate components of the model are created using different silicone thickness, shore hardness, and colors and are manually assembled.…”

“… 6 , 7 , 8 , 9 , 10 , 11 However, commercially available materials for 3D printing provide suboptimal elastic properties, strength, and texture for surgical procedures. 6 , 9 , 10 , 12 , 13 , 14 , 15 Silicone has been used for variety of medical applications because its physical properties are similar to those of human soft tissues. 16 Despite the growing demand for innovation, current 3D printing technology for silicone modeling is considered inadequate for the production of complex congenital heart disease models.…”

Does the PolyJet Printing Technology Affect Mechanical Properties of 3D Printed Synthetic Tissue?

“…Overall thinner liver samples that were less compliant saw a greater difference between the two printers. It was noted previously that DA configurations are able to simulate liver tissue at low forces which correspond to small displacements and thus lower stiffness values [6]. Similar to the J750 DA printer samples, J5 DA printed liver samples also achieve this criteria thus making them acceptable to use in benchtop testing as they fall within the use conditions that would be experienced.…”

“…Porcine tissue testing was previously conducted in prior mechanical testing and was used to compare to 3D printed samples [5,6]. Porcine tissue was used to compare the printed tissues due to this being a common pre-clinical animal model.…”

“…This tissue was collected from butchers and preclinical research facilities and frozen at -80C either immediately after termination or 2-4 hours after termination. Samples were allowed to thaw in an insulated cooler prior to testing for around 14 hours [5,6].…”