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UBC Theses and Dissertations

Investigations into inkjet cell printing hydrodynamics through microscopy imaging techniques Cheng, Eric


Inkjet bioprinting technology aims to accurately and precisely dispense biological materials in a spatially predefined pattern within a three-dimensional space. The technology has a multitude of applications in the biomedical field such as in drug discovery and tissue or organ engineering. However, there are known limitations in an inkjet nozzle's capabilities in dispensing cells as the cell ejection rate does not follow any predictable distributions. In this work, the cell behaviors within a piezoelectric nozzle due to droplet ejection were classified through high speed brightfield imaging. With each ejected droplet, one of three cell behaviors was observed to occur: cell travel, cell ejection, or cell reflection. Cell reflection is an undesirable phenomenon which may adversely affect an inkjet's capability to reliably dispense cells. To further study how the hydrodynamics within a nozzle can influence the cell's behavior, µPIV was performed to identify the flow field evolution during droplet ejection. Through the study of cell motion, it was observed that the viscosity of the media in the cell suspension plays an important role in influencing the cell behavior. This was experimentally studied with the tracking of cells within the inkjet nozzle in a higher viscosity 10% w/v Ficoll PM400 cell suspension. As hypothesized, the addition of Ficoll PM400 was effective in preventing the occurrence of cell reflection which promises to increase the reliability in inkjet bioprinting systems.

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