Modeling of variational gradient porous architecture with multidirectional filament deposition in 3D scaffolds

Porous scaffolds with interconnected and continuous pores have recently been developed to stimulate tissue regeneration. Even though few researches have focused on the internal architecture of porous scaffolds but concluded that properly interconnected and continuous pores with spatial distribution might perform diverse mechanical, biological and chemical functions of a scaffold. Thus the need for reproducible and fabricatable scaffold design with controllable gradient porosity is obvious but is hardly achieved because of design and fabrication limitations. In this paper, a novel functionally gradient variational porosity architecture has been proposed with continuous material deposition planning scheme. The medial axis transformation for the scaffold has been calculated to generate an internal feature of the geometric domain. The medial axis is then used as a base to develop the medial boundary to define the medial regions. Then the complex internal architecture of scaffolds is divided into sub-regions using the ruling lines that are generated between the slice's contour and the medial boundary. The desired controlled variational porosity along the scaffold architecture has been achieved with the combination of two geometrically oriented consecutive layers while meeting the tissue scaffold design constraints. This ensures truly porous structures in every direction as well as controllable porosity with interconnected pores along the scaffold architecture. The proposed methodology has been implemented and illustrative examples are also provided. A sample designed structure has been fabricated with a NC motion controlled micro-nozzle deposition system.