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International Journal of Bioprinting Nozzle optimization for multi-ink bioprinting

Figure 5. Line structure printing test using the proposed nozzles and their comparisons against T-junction nozzle. (A) Schematics of the T-junction
nozzle and asymmetry nozzles (I–III) prepared for both simulation and experiment. (B) T-junction and three asymmetrical nozzles fabricated using vat
polymerization printing. (C) Comparison of transition lengths between the T-junction nozzle and asymmetrical nozzles based on printing experiments.
Experimental data were collected five times for each sample. Data are presented as mean ± S.D.; * p < 0.05.

6.5 mm when 0.5 wt% SA ink switched against 2.0 wt% compared to 15.3 ± 1.7 mm when 2.0 wt% SA ink switched
SA ink, significantly longer than the 6.3 ± 1.8 mm when against 0.5 wt% SA ink (Figure 6D; T-junction, cross,
2.0 wt% SA ink switched against 0.5 wt% SA ink in the category 1 in each nozzle type). Although the transition
T-junction nozzle (Figure 6D; T-junction, cross, category 2 length using the cross nozzle was longer than that of the
in each nozzle type). A significant difference was observed T-junction nozzle for the same ink combination, the length
between the transition lengths. In addition, the widths of was approximately five times shorter when 0.5 wt% SA ink
the transition area of the printed line structures were 1.6– was switched with 2.0 wt% SA ink, accounting for the effects
2.2 mm, which showed no significant difference (Figure of viscosity and nozzle shape on the switching process. This
S5A, Supporting Information). The transition areas of the setup allows for the testing of various ink combinations in
printed line structures are shown in Figure S5B, Supporting numerical simulations for single-nozzle printing.
Information. Switching low-viscosity ink with high fidelity Further exploration was conducted with 1.0 wt% SA
in the T-junction nozzle proved challenging. Conversely, ink against itself in a T-junction nozzle. The simulation
the transition length was 9.8 ± 4.5 mm when 2.0 wt% SA showed that switching occurred when the liquid reached
ink was switched with 0.5 wt% SA ink in the cross nozzle, the corner of the conjunction area (Figure 7A). We

Volume 10 Issue 5 (2024) 162 doi: 10.36922/ijb.4091