Page 53 - IJB-8-2

RESEARCH ARTICLE

Computational Fluid Dynamics Assessment of the Effect

of Bioprinting Parameters in Extrusion Bioprinting

Rashik Chand , Beni Shimwa Muhire , Sanjairaj Vijayavenkataraman *
1,3
2
1
1 The Vijay Lab, Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
2 Department of Mechanical Engineering, United Arab Emirates University, Al Ain, United Arab Emirates
3 Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn,
NY 11201, USA.

Abstract: Wall shear stress is the most critical factor in determining the viability of cells during the bioprinting process, and
controlling wall shear stress remains a challenge in extrusion bioprinting. We investigated the effect of various bioprinting
parameters using computational simulations on maximum wall shear stress (MWSS) in the nozzle to optimize the bioprinting
process. Steady-state simulations were done for three nozzle geometries (conical, tapered conical, and cylindrical) with
varying nozzle diameters (0.1 mm–0.5 mm) at different inlet pressure (0.025 MPa–0.25 MPa) as inlet conditions. Non-
Newtonian power law was used to model the bioink rheology and four different bioinks with power-law constants ranging
from 0.0863 to 0.5050 were examined. To capture the dynamic behavior of the bioink and the thread profile of the extruded
bioink, transient simulations were carried out. Our results indicate that although the MWSS is lowest in the cylindrical nozzle,
this stress condition lasts for a longer portion of the nozzle and for the same inlet pressure and nozzle diameter, the mass flow
rate is lower compared to the tapered conical and conical nozzle, contributing to lower cell viability.

Keywords: Computational fluid dynamics; Non-Newtonian fluid; Power-law fluid model; Extrusion bioprinting;
Bioprinting parameters
*Correspondence to: Sanjairaj Vijayavenkataraman, Global Network Assistant Professor of Mechanical Engineering, Experimental Research
Building (C1-039), NYU Abu Dhabi, Saadiyat Campus P.O. Box 129188 Abu Dhabi, United Arab Emirates; vs89@nyu.edu
Received: December 5, 2021; Accepted: January 20, 2022; Published Online: March 22, 2022

Citation: Chand R, Muhire BS, Vijayavenkataraman S., 2022, Computational Fluid Dynamics Assessment of the Effect of Bioprinting
Parameters in Extrusion Bioprinting. Int J Bioprint, 8(2):545. http://doi.org/10.18063/ijb.v8i2.545

1. Introduction materials with high cell density can be used. In extrusion
bioprinting, continuous bioink filaments are deposited
Bioprinting refers to the biofabrication involving specially layer by layer on a surface mechanically by displacement
designed three-dimensional (3D) bioprinters that deposit of a piston or screw or using pneumatic pressure . In
[2]
bioinks in a controlled manner to create tissues and contrast, inkjet bioprinting is comparable to conventional
biocompatible structures. Bioinks are composed of living two-dimensional (2D) printing and cannot generate a
cells suspended in a biocompatible polymer (hydrogel) continuous flow, whereas in laser-assisted bioprinting,
in the presence of other additives, such as differentiation a high-intensity laser is used to deposit the bioink
and growth factors, or other biomaterials. Bioprinting is without applying direct force to the cell and finally,
increasingly being considered an ideal tool for biofabricating stereolithography makes use of light-sensitive polymer
rejection-free tissues and organs for transplantation . material . While the advantage of extrusion-based
[1]
[3]
Bioprinting can be categorized into four main bioprinting is that it can create more clinically relevant
technologies: Micro-extrusion, inkjet, laser assisted, and printed structures using bioink with higher viscosity,
stereolithography. Among these categories, extrusion- cell viability in extrusion bioprinting ranges from 40 to
based bioprinting is the most used due to its relative 80% which is lower compared to >85% in inkjet-based
simplicity, affordability, and scalability as high viscous bioprinting and >95% in laser-assisted bioprinting [4,5] .

© 2022 Author(s). This is an Open-Access article distributed under the terms of the Creative Commons Attribution License, permitting distribution and
reproduction in any medium, provided the original work is properly cited.
45