UBC Theses and Dissertations

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UBC Theses and Dissertations

Enhanced piezoelectric drop-on-demand cell dispensing through neutral buoyancy Chahal, Daljeet


Micro dispensing of cell based suspensions offers enhanced precision and accuracy for a wide variety of applications including high throughput cell based assays, single cell analyses and tissue engineering. One technology that offers such promises is piezoelectric inkjet printing. However, the small size scale of internal system features makes it difficult to eject particle based suspensions due to undesirable phenomena within the suspension. In particular, it has been hypothesized that inkjet dispensing of cell based suspensions has been hindered by sedimentation and aggregation of cells. The objective of this thesis was to investigate the phenomenon of cellular sedimentation and determine whether it affects piezoelectric dispensing reliability, and to devise a method to mitigate this phenomenon. The challenge in stabilizing suspensions to halt sedimentation lies in constraints involving cellular viability, and the rheological limitations imposed by the capability of the inkjet system itself. We achieved stabilized cellular suspensions through the use of a sucrose co-polymer, Ficoll-PM400. We show herein that stabilizing the suspension to be dispensed through this method greatly improves the reliability of the system over long periods of time, and increases the consistency of cell counts. Cell viability was shown to remain constant even when suspended for periods of 1 hour. The change in viscosity of the suspension also decreased the amount of clogging events that have hampered particle based inkjet dispensing approaches. Lastly, we give recommendations regarding future work on this technology.

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Attribution-NonCommercial-NoDerivatives 4.0 International