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International Journal of Bioprinting Nozzle optimization for multi-ink bioprinting

Figure 2. Consistency test of numerical simulation against experiment by testing the switching behavior in different shape of nozzle. (A, B) Single nozzle
shapes prepared for simulation (A) and experiment (B); scale bar = 1 mm. (C) Effects of single nozzle’s conjunction angle on switching efficiency (Se) at
1.0 wt% SA solution in the experiment (black bars) and simulation (white bars). Experimental data were obtained five times for each sample. Data are
expressed as mean ± S.D.; * p < 0.05.

the simulation results, demonstrating that the effects switch between different viscous bioinks is necessary for
of viscosity on switching could be effectively analyzed achieving high-resolution multi-ink printing.
through numerical simulations.
3.3. Effect of asymmetrical nozzle shape on
Furthermore, the effect of viscosity was also analyzed switching efficiency
in nozzles with different conjunction angles (Figure 2A) We previously demonstrated that the shape of the
using numerical simulations (Figure 3D). The nozzle with conjunction area in a single nozzle influences Se.
a 15° conjunction angle exhibited the highest Se for any Considering this impact, we hypothesized that flow
ink combination, while the nozzle with a 75° conjunction direction is a critical factor for efficiently switching
angle had the lowest efficiency for any combination. These between different viscous inks. To test this hypothesis, the
results demonstrated that viscosity significantly affects impact of ink flow direction on Se was investigated using
switching efficiency in any nozzle configuration used in this five types of asymmetrical nozzles (Figure 4A; labeled
study. Therefore, developing a nozzle that can efficiently I–V). In numerical simulations, 1.0 wt% SA solution was

Volume 10 Issue 5 (2024) 158 doi: 10.36922/ijb.4091