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Controlling Droplet Impact Velocity and Droplet Volume Improves Cell Viability in Droplet-Based Bioprinting
droplet volume of 20 nL per spot and total printing duration Organoid Construction-are Biomaterials Dispensable? Trends
of 2 min for each printed layer are recommended for Biotechnol, 34:711–21.
maintaining a high cell viability of > 90%. The generated https://doi.org/10.1016/j.tibtech.2016.02.015
results from this work using cell-laden PBS droplets serve 6. Gruene M, Pflaum M, Hess C, et al., 2011, Laser Printing of
as a baseline for other droplet-based bioprinting techniques Three-dimensional Multicellular Arrays for Studies of Cell-
that involve contactless jetting of nano-liter cell-laden
droplets across a nozzle-substrate distance. The ability to Cell and Cell-Environment Interactions. Tissue Eng Part C
maintain high cell viability and proliferation rate of the Methods, 17:973–82.
printed cells by controlling the droplet impact velocity https://doi.org/10.1089/ten.tec.2011.0185
and droplet evaporation is useful for various bioprinting 7. Ng WL, Lee JM, Zhou M, et al., 2020, Hydrogels for 3-D
applications, such as fundamental studies of cell-cell or Bioprinting-based Tissue Engineering. In: Narayan R, editor.
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https://doi.org/10.1016/b978-0-08-102663-2.00008-3
Acknowledgments 8. Kathawala MH, Ng WL, Liu D, et al., 2019, Healing of
This study is supported under the RIE2020 Industry Chronic Wounds an Update of Recent Developments and
Alignment Fund – Industry Collaboration Projects (IAF- Future Possibilities. Tissue Eng Part B Rev, 25:429–44.
ICP) Funding Initiative, as well as cash and in-kind https://doi.org/10.1089/ten.teb.2019.0019
contribution from the industry partner, HP Inc., through 9. Rose JC, De Laporte L, 2018, Hierarchical Design of Tissue
the HP-NTU Digital Manufacturing Corporate Lab. We Regenerative Constructs. Adv Healthc Mater, 7:1701067.
would also like to acknowledge and thank the D300e HP https://doi.org/10.1002/adhm.201701067
team for supplying the C8 cell-dispensing cassettes for
the experiments and Professor Zhou Kun’s group for the 10. Ng WL, Goh MH, Yeong WY, et al, 2018, Applying
use of their rheometer. Macromolecular Crowding to 3D Bioprinting: Fabrication of
3D Hierarchical Porous Collagen-based Hydrogel Constructs.
Conflict of interest Biomater Sci, 6:562–74.

The authors declare no potential conflicts of interest. https://doi.org/10.1039/c7bm01015j
11. Lee JM, Suen SK, Ng WL, et al., 2020, Bioprinting of
Author contributions Collagen: Considerations, Potentials, and Applications.

The manuscript was written through contributions of Macromol Biosci, 21:2000280.
all authors. All authors have given approval to the final https://doi.org/10.1002/mabi.202000280
version of the manuscript. 12. Osidak EO, Kozhukhov VI, Osidak MS, et al., 2020, Collagen

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