The Use of Schwartz Geometries for Scaffold Design in Tissue Engineering Applications

Additive biomanufacturing processes are increasingly recognised as ideal techniques to produce scaffolds for tissue engineering applications. Scaffolds provide a temporary mechanical and vascular support for tissue regeneration while shaping the in-growth tissues. These scaffolds must be biocompatible, biodegradable, with appropriate porosity, pore structure and pore distribution and optimal vascularisation, with both surface and structural compatibility. Surface compatibility means a chemical, biological and physical suitability to the host tissue. Structural compatibility corresponds to an optimal adaptation to the mechanical behaviour of the host tissue. Recent advances in the tissue engineering field are increasingly relying on modelling and simulation. The design of optimised scaffolds based on the fundamental knowledge of its microstructure is a relevant topic of research. This paper proposes the use of novel geometric structures based on the Triple Periodic Minimal Surfaces formulation, namely the Schwartz primitives, one of the a sub-classes of Triple Periodic Minimal Surfaces. Schwartz primitives enables the design of vary high surface-to-volume ratio structures with high porosity and mechanical/vascular properties. With the use of a computational tool combining structural, computational fluid dynamics and topological optimisation schemes, it is possible to predict and optimise both mechanical and vascular behaviour of scaffolds for soft and hard tissue applications, with different topological architectures and levels of porosity. This tool is particularly important to quantify the structural heterogeneity and scaffold mechanical properties with a designed microstructure subjected to either a single or a multiple load distribution. This computational tool enables the simulation of biological flows in vascular passages of scaffolds. The blood flow considered in this study is a complex fluid comprising a suspension of red blood cells, white blood cells and platelets within a newtonian plasma.