Fluid Permeability of Graded Porosity Scaffolds Architectured with Minimal Surfaces

The natural local porosity variation in the native tissue can be replicated by graded porosity scaffolds. Scaffolds with radial porosity distribution can be a solution to improve both mechanical and biological functions of the biomimetic scaffolds. In the present study, fluid permeability as a quantitative indicator of biological performance is studied numerically and experimentally for different pore shapes and porosity distribution patterns in the scaffolds designed on the basis of triply periodic minimal surfaces (TPMSs). Among the uniform porosity scaffolds, those designed on the basis of P* (P surface) and Y** (G surface) showed the highest permeability. In the radially graded porosity scaffolds with linear porosity distribution, permeability was found to be about twice more sensitive to the peripheral porosity than the porosity at the center. The results suggest that the permeability gradient parameter relationships can follow different trends depending on the pore shape as opposed to the conventional uniform porosity scaffolds. This implies the need for the design maps that were developed to choose appropriate scaffold pore design parameters. Finally, experimental permeability measurement was performed via a constant head permeability test, and the effect of test parameters (i.e., fluid height) was discussed.