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Effects of topology optimization in multimaterial 3D bioprinting of soft actuators

Figure 3. Two-material topology optimization algorithm utilized in this study.

The equivalent optimal solution for 3D printing or using high-molecular-weight polymer inks, to
of two-material configuration at actuator layers is preserve the structural integrity of the 3D-printed
illustrated in Figure 4 where the volume fraction hydrogels on extrusion . Wet spinning and
[37]
constraint is applied using two different materials solvent casting are other common methods of 3D-
for each layer. The results of optimization with printed hydrogel extrudate solidification .
[38]
respect to volume fraction and objective function In this paper, however, the liquid hardening
over a number of iterations are presented in method was applied to chitosan hydrogel . The
[22]
Figure 5. These results demonstrate the graduate TO algorithm is exported to an EnvisionTEC
decrease of the objective function with increasing GmbH Bioplotter. A mixture of chitosan (Sigma-
number of iterations until reaching a minimum at Aldrich, Australia) and acetic acid solution poured
iteration 19 when the volume fraction criterion is into the bioplotter syringe. The hardening of the
fulfilled. extruded strand was carried out in 0.25 M sodium

3 Fabrication of the 3D bioprinted actuator hydroxide solution. The statistical significance of
the 3D printing procedure for developing chitosan
3D bioprinting fabrication of hydrogel-based actuators has already been developed and can be
soft actuators requires determination of accurate accessed in earlier works [22,39] . The two-material
process parameters to achieve timely coagulation bioprinted actuator is shown in Figure 6. 3D-
of the extruded strand from the printer nozzle. The printed hydrogel pastes were made with different
previous studies have utilized various synthesis molecular weights and concentrations to function
techniques, such as using cross-linking agents as two different materials with varying density

54 International Journal of Bioprinting (2020)–Volume 6, Issue 2