Investigation of the Hydrodynamics of Suspended Cells for Reliable Inkjet Cell Printing
Bibliographic record
Abstract
Reliable inkjet drop-on-demand dispensing of cells has numerous applications including cell assays and tissue engineering. Previous work on inkjet cell printing has demonstrated that the cell count per droplet is inhomogeneous and does not follow the expected Poisson distribution. In the present work, the flow-induced cell behaviour is characterised to better understand the hydrodynamic mechanisms behind unreliable cell printing. A glass piezoelectric inkjet nozzle with an 80 μm diameter orifice is mounted on a PDMS cast which acts as a refractive index matching material for cell tracking through an inverted microscope. Droplet formation is achieved by a bipolar waveform. A high-speed camera focused on the centre plane of the nozzle captures images which are then analysed by a cell tracking algorithm to obtain the horizontal and vertical position of the cells over time. High-speed tracking of cells within a transparent inkjet nozzle revealed three possible cell behaviours caused by the formation and break-off of droplets. These behaviours are cell travel, cell ejection and cell reflection, determined as a function of the position of the cell at the onset of droplet formation. The first behaviour, cell travel, is characterised as the displacement of the cell towards the orifice during droplet formation followed by a small backwards motion due to the retracting meniscus after droplet pinch-off. Cell travel results in a net forward displacement of the cell towards the nozzle orifice. The second observed cell behaviour is cell ejection, where a cell is ejected with a droplet and can no longer be observed within the nozzle after the droplet break-off. The third observed cell behaviour is cell reflection. In this case, hydrodynamic forces produced during droplet ejection acts on the cell to move it further away from the nozzle orifice resulting in a net displacement of the cell away from the orifice after droplet ejection. Through the cell tracking information, it is hypothesized that cell reflection is caused by fluid flow reversal during the droplet ejection process. As a result of cell reflection, certain cells within a region close to the orifice will not be printed; instead they are pushed to a location further away from the orifice. Therefore, mapping of cell positions before droplet formation is performed to identify regions within the nozzle that exhibit a high probability of cell ejection and reflection. Overall, the results from this study will greatly contribute to our understanding of the cell printing process, which will allow us to optimize current inkjet systems for cell printing applications.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".