Page 379 - IJB-10-1

International Journal of Bioprinting Design of dual-unit porous scaffold

Figure 1. Design idea of gradient biomedical scaffolds using the new dual-unit minimal surface continuous transition connection strategy.
Table 1. Function expressions of the three TPMS units

TPMS Function expression
az
ax
P [cos() cos( ay )cos() C]
P
ax
az
ay
G [cos() sin( ay )cos()sin( az )cos()sin( ax ) C]
G
ax
az
ay
D [cos() cos( ay)cos() sin( ax )sin()sin( az ) C]
D
the TPMS structure period, and C is used to control the 2 mm, 60%, and 3 mm, respectively. The morphologies
porosity of the scaffold. of the final continuous transition connected models are
In this work, in order to obtain the scaffolds with shown in Figure 2. Figure 2A shows the direct connection
39
continuous transition of different units, a continuous of two TPMS units in the previous work. The continuous
function is used and the equation is as follows: 20 transition connection strategy can effectively improve
the connection condition of different units. In order

1 2 (I) to understand the effects of unit size and porosity on
c
2
2
2
2
1 e r ( 2 ( x y )) 1 e r ( 2 ( x y )) the mechanical properties of scaffolds, based on D-G
combined structure, three structures with different area
where r controls the radius of the inner unit structure; ratios of internal G structures, two scaffolds with different
the parameter θ (θ>0) is used to control the intensity of unit sizes (1.5 mm and 1 mm), and two scaffolds with
the transition of the two-unit structures; φ is the outer different porosity (50% and 70%) were designed, named
1
unit structure function expression; and φ is the inner as 4-5 D-G, 2-5 D-G, 1-5 D-G, D-G (1.5 mm), D-G (1
2
unit structure function expression. The expressions of the mm), D-G (50%), and D-G (70%), respectively. The
final dual-unit connected scaffolds are shown in Table 2. continuous functions were imported into Mathematica
In this paper, the porous scaffolds are named in the form 12.0 software and then parameterized into a scaffold
of A-B, where A represents the outer unit structure of the model with a height of 15 mm and a diameter of 10 mm.
scaffolds, and B represents the inner unit structure of the The design model of the scaffolds is shown in Figure 3.
scaffolds. The scaffold is designated as P-G, G-P, G-D,
D-G, P-D, and D-P based on the three fundamental unit 2.2. Preparation of the porous scaffolds
structures of P, G, and D. The element size, porosity, and Commercial TC4 (Ti6Al4V) alloy powder (JIUHE Frontier
internal structure radius of these six scaffolds were set at Innovation of Science and Technology (Shanghai) Co., Ltd)
Volume 10 Issue 1 (2024) 371 https://doi.org/10.36922/ijb.1263