Abstract
A CAD system of structures based on convex polyhedra units has been created for use with Rapid Prototyping (RP) technology in tissue engineering. The system consists of a basic library of units that can assemble uniform matrices of various shapes. Each open-cellular unit is a unique configuration of linked struts. Together with an algorithm which allows the designer to specify the unit cell and the required dimensions, the system is able to automatically generate a structure that is suitable for the intended application. Altering the parameters can easily change the desired shape and spatial arrangement of the structures. The quality of the fabricated structures is consistent and readily reproducible.
To verify that the algorithm works, a disc shape scaffold is designed to be fabricated using Selective Laser Sintering (SLS). In this disc-shaped design, four different strut lengths are used, resulting in four different pore sizes and porosity. Scaffolds of the one-unit layer cells were built using Duraform (TM) Polyamide are then examined under light microscope to check the consistency and reproducibility of the microstructures.
It is found that the microstructures of the scaffolds fabricated are consistent and can be readily reproduced. One limitation is found to be in removing the trapped powder of the pores in the scaffolds produced. This is especially difficult for small pore sizes below 0.500mm (500 mu m) in diameter. Ultrasonic cleaning was employed to test if it can remove the powder still trapped after manual cleaning. This has shown only limited success.