Biomimetic Structured Porogen Freeform Fabrication System for Tissue Engineering
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Fig. 4. Schematic view of Solidscape system.
Fig. 5. Digital photograph of (A) Inkjet print heads; (B) Solidscape Modelmaker II RP
machine.
2.2 Porogen design and fabrication
2.2.1 CAD designs of porogen
Pro/E software package was used to design porogens and then transfer the design into STL
format which is required by Modelwork software to run the RP machine. In order to
simulate the global pore structure present in bone tissue, those porogens were designed
with fully interconnected voids. They had different design with different size, varying
porosity and internal architectures. Figure 6 (A) shows a fabricated porogen design, its CAD
model is shown in Figure 6 (B). Figure 6 (B) to (F) are all possible porogen designs. After
fabrication and injection tests, considering the uniformity and ease in making the porogens
we finalized our design which is shown in Figure 6 (C). In this design, each void of the
square scaffold is in the shape of a cube and is separated from adjacent voids by struts on
four of its sides. Hence the resulting structure of the scaffold was a series of rods with
rectangular cross-sections connected to one another. The dimensions of the voids and the
rod cross sections were equal and constant throughout the scaffold volume. The overall
scaffold volume was cube in shape that is easy for the machine to make. Scaffold designs
were created for a constant pore size of 600μm, 400μm, 300μm, and 200μm in squware sides.
A B