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Arguchinskaya, et al.
of the cross-section number on the quality of supports creation (involved subtracting the model of thyroid
obtained are presented in Figure 3A. cartilage from the extruded projections) could lead to the
The volume of the support increases with an formation of areas with walls thinner than the size of a
increment of slice number. An intermediate value (2 mm) dispenser nozzle. In this case, a proper slicing procedure
was approved for the study. The use of a smaller step (g-code creation) would fail. Ultimately, it would lead to
unnecessarily complicates the model increasing the areas where the main material will not have support. In
number of polygons (6.81 × 104 for 0.5 mm step), thus, Figure 4A-C, such an analysis is presented by means of
making the process of the support creation more time Meshmixer for the supports with different steps of cross-
consuming, necessitating further modification which section (conversation into the solid body was carried out
would toughen both software and hardware.requirements. in accordance with standard software parameters). The
Analysis of the effect of each slice (Figure 3B) on disagreement of wall thickness with minimal possible
the formation of the supporting part of the scaffold showed value is specific for all variants. To solve this issue, three
that the greatest increase in the volume of the support is options were applied in “Accurate mode,” as shown in
determined by two sets of sections. The first set, which Table 2.
is in the range of 2÷6 mm, is responsible for the base of The considered parameters refer to the number of
the support. The second set (12÷24 mm) contributes to the voxels used in the courses of primary (“Solid accuracy”)
model due to a slope of thyroid cartilage walls. A smaller and secondary (“Mesh density”) approximation of the
impact is made by the group of slices in the range of 30÷34 model, as well as the restriction of minimal thickness.
mm. However, they are responsible for an important
part of the model which especially needs support. These Table 2. Meshmixer conversation parameters
elements are shown in the upper right part of Figure 1C.
Procedure Solid Mesh Min
3.3. Assessment and modification of the support accuracy density thickness, mm
wall thickness 1 128 128 0.52
Further processing of support model included 2 128 128 1.03
modification of wall thickness. The process of supporting 3 96 512 0.52

A B C

Figure 2. The process of support creation. (A) Cross-sections with 2 mm step. (B) The volume formed by extruding of each slice to the base.
(C) The complete support model obtained by subtracting the thyroid cartilage model from the model in Figure 1(A).

A B

Figure 3. The effect of cross-section number on the quality of supporting part of the scaffold. (A) Dependence of the overall volume (model
quality) and a number of polygons (model complexity) on the step of the cross-section in the range of 0.5÷8 mm. (B) Volume increases for
each new slice (from the bottom one) and area of each section for 2 mm step.
International Journal of Bioprinting (2021)–Volume 7, Issue 2 107