Investigation of cell-viability in the bioprinting process

Abstract: The human society has throughout history been faced with great challenges. These challenges however hold the opportunity for us humans to learn and grow as a species in whole. As the human population is increasing, more attention has been focused to the medical eld to deal with the challenge of curing and treating people in larger scales at a faster rate. A particular challenge today is to meet the high demand in organ transplants. The number of human donors is scarce relative to the demand, and the transplantation is never guaranteed to be successful. Therefore allot of research is being conducted regarding the potential of 3D-bioprinting. 3D-bioprinting is an interesting eld with a lot of potential where the ultimate goal is to produce human organs for transplantation with the use of a 3D-printer. However, there are still many cases in which the cell viability in the bioprinting process is signicantly low. If the reason is biological or mechanical due to the strains in the ow through the bio- printer is sometimes unclear. Here presented is an investigation on the uid stresses present in the nozzle of the bioprinter. This is done by simulating the ow through the nozzle tip using CFD software and calculating the principal stresses on the cells in the post processing step. By using simple elastic deformation models the total area strain is calculated along the particle track of a cell to predict how the cells may deform throughout its particle track in the nozzle. It is found that the uid stresses present in the converging nozzle considered in this case are signicant, and cannot be excluded as a prime reason for the death of the cells in the bioprinting process. Due to the non-newtonian character of the bioink considered in this case, the cells close to the wall experience principal stresses signicantly higher than in the mainow. Generally the character of the stresses experienced by the cells along their particle tracks is observed to be highly exponential, thus it proposed for future work to investigate how much the maximum magnitude of the stresses at the outlet can be decreased by considering shorter nozzle tips.