Test and validation of a hybrid and multi-material 3D printer to mimic soft living tissues
Document typeMaster thesis
Rights accessOpen Access
For the purposes of developing a multi material 3D printer, hybrid to the Fused Filament Fabrication (FFF) and Direct Ink Writing (DIW) technologies, to mimic living tissues, the 3D printing of soft Thermoplastic Polyurethanes (TPU) by DIW is studied to reach a hardness scale so far not crossed with the filament technology. The creation of several pieces through CAD lets a pressurized syringe to be fixed to the printer’s head upon which is also mounted two UV lights to cure the liquid polymer, solidifying on the bed. The soft polyurethanes at the outcome must match their numerical model with the best accuracy since the objective of the main project QuirofAM is to create prototypes of organs to train surgeons to prepare their complex surgical operations. For this matter, the different printing parameters (pressure, extrusion speed, layer thickness or UV light power), specific to each sample, must be identified with precision. Finally, the successful printed TPUs are compared to homologous cast ones by Shore hardness trials and Warner-Bratzler cuttings, as well as organ tissues. The results are various. On the one hand, the printing method can give softer tissues than casting, and getting similar hardness to living tissues is achievable, though it is observed an increasing printing difficulty with softness. On the other hand, the Warner-Bratzler cutting is not conclusive and, at equal hardness, it requires much more force to cut a printed TPU than an organ tissue. Other tests such as Dynamical Mechanical Analysis (DMA) should be conducted in the future to enhance the characterization of the soft polyurethanes.
SubjectsMaterials -- Analysis, Three-dimensional printing, Polyurethanes, Materials -- Anàlisi, Impressió 3D, Poliuretans