Page 152 - IJB-10-6

International Journal of Bioprinting Fluid mechanics of extrusion bioprinting

role in the bioprinting process. Successful printing with Acknowledgments
good extrudability and filament fidelity requires a shear-
thinning (thixotropic) bioink with a reasonable viscosity The authors would like to thank the University of
recovery rate. An increase in the elastic modulus of a Saskatchewan and the Natural Sciences and Engineering
viscoelastic bioink improves filament fidelity but reduces Research Council (NSERC) for their financial support.
cell viability. Therefore, a successful bioprinting requires
the careful preparation of bioink and rigorous selection Funding
of printing parameters, such as extrusion pressure, This research was financially supported by the University
printing speed, and nozzle size. As an emerging aspect of Saskatchewan Dean’s Scholarship and the Devolved
of extrusion bioprinting, multi-material bioprinting has Scholarship from the Department of Mechanical
garnered significant attention. Printing multi-material Engineering for the first author, and by the Natural
filaments with accurate control over their composition is Sciences and Engineering Research Council (NSERC)
key to addressing the challenge of printing heterogeneous funds for the co-authors. Grant numbers: RGPIN 06396-
constructs that mimic the zonal heterogeneity of native 2019, RGPIN 04981-2022
tissues. Although various multi-material printing
methods have been developed and have achieved some Conflict of interest
success, printing a construct that can mimic the structure
and cellular composition of natural tissue remains a Xiongbiao Chen serves as the Editorial Board Member
significant challenge. This challenge is associated with of the journal, but did not in any way involve in the
several issues, including the printability and discrepancies editorial and peer-review process conducted for this paper,
between the printed construct and its CAD design, as well directly or indirectly. Other authors declare they have no
as difficulties in mixing and flow control that can affect competing interests.
the mechanical properties of the construct and potentially
damage cells. Furthermore, reducing the transition Author contributions
length during the composition change can improve the Conceptualization: Reza Gharraei, Donald J. Bergstrom,
resolution of multi-material bioprinting heads, especially Xiongbiao Chen
when printing constructs with zonal heterogeneity. Supervision: Xiongbiao Chen, Donald J. Bergstrom

A well-designed multi-material printing head can Writing – original draft: Reza Gharraei
alleviate the negative effects of the shear and extensional Writing – review & editing: Donald J. Bergstrom, Xiongbiao
stresses applied on the cell during extrusion. Simulations Chen, Reza Gharraei
play a crucial role in the design of multi-material heads,
as they provide detailed information about the stress field Ethics approval and consent to participate
and concentration of precursors. This allows designers to Not applicable.
understand the dynamics of the head and address potential
operational issues before fabrication. The primary challenge Consent for publication
in CFD simulations of the bioprinting process is accurately
representating the rheological behavior of bioinks due to Not applicable.
their time-dependent and viscoelastic natures. It becomes
more challenging or worse for multi-material heads, Availability of data
where the viscoelastic properties of bioinks change during Not applicable.
mixing, thereby requiring more complex constitutive
equations for modeling the viscoelastic behavior of their References
mixtures. Finding suitable viscoelastic models for various
bioinks and using CFD to simulate bioink flow during 1. Derakhshanfar S, Mbeleck R, Xu K, Zhang X, Zhong W,
extrusion and deposition on the stage can provide much Xing M. 3D bioprinting for biomedical devices and tissue
reliable information on the process-induced forces, fiber engineering: a review of recent trends and advances. Bioact
diameter, and printability of the bioink. Such information Mater. 2018;3(2):144-156.
would be difficult, if not impossible, to capture through doi: 10.1016/j.bioactmat.2017.11.008
experiments alone. Developing composition-dependent 2. DeSimone E, Schacht K, Jungst T, Groll J, Scheibel T.
constitutive equations that can model the behavior of Biofabrication of 3D constructs: fabrication technologies
miscible viscoelastic fluids as they are being mixed remains and spider silk proteins as bioinks. Pure Appl Chem.
a significant challenge in this field, highlighting a critical 2015;87(8):737-749.
area for future research. doi: 10.1515/pac-2015-0106

Volume 10 Issue 6 (2024) 144 doi: 10.36922/ijb.3973