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Simulated stress mitigation strategies in embedded 3D bioprinting



Leanne Friedrich, Ross Gunther, Jonathan Seppala


Extrusion-based 3D bioprinting is a powerful tool for fabricating complex cell-laden constructs. Embedded Ink Writing (EIW) is an extrusion-based printing technique wherein a nozzle embedded into a support bath writes continuous filaments. Because it allows for low-viscosity inks, EIW is particularly useful for bioprinting. One of the largest challenges in extrusion-based bioprinting is limiting damage that cells experience inside of the nozzle. Longer shear stress durations and higher shear stress magnitudes lead to more damage. Shape fidelity is also critical for bioprinting. Filaments in EIW can exhibit defects like sharp edges and large aspect ratios, which can lead to porosity, surface roughness, and poor mechanical properties in the final part. We use numerical computational fluid dynamics simulations in OpenFOAM to evaluate whether common shear stress mitigation techniques improve cell viability without causing shape defects. Critically, we find that using a conical nozzle, increasing the nozzle diameter, decreasing the print speed, and decreasing the ink viscosity can improve the viability of magnitude-sensitive cells, but using a conical nozzle, increasing the nozzle length, and decreasing the print speed can increase damage in duration-sensitive cells. Additionally, using a conical nozzle or a larger nozzle can lead to larger shape defects in printed filaments. Material selection and printing parameter selection in embedded 3D bioprinting should take into account allowable shape defects, allowable cell damage, and cell type.
Physics of Fluids


3D-printing, bioprinting, extrusion, Herschel-Bulkley, OpenFOAM, simulation


Friedrich, L. , Gunther, R. and Seppala, J. (2022), Simulated stress mitigation strategies in embedded 3D bioprinting, Physics of Fluids, [online],, (Accessed June 23, 2024)


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Created August 30, 2022, Updated November 29, 2022