Valve-inspired design for minimal surfaces-based porous scaffolds: Decoupling permeability from structure stiffness

In fields such as medical implants and heat exchangers, structures usually need both good mechanical and mass transport properties (including permeability), but their coupling makes independent regulation difficult, hindering the development of porous scaffold structures with multi-functional capabilities. One effective solution to this challenge is to reduce or eliminate the strong coupling between these properties. Most current methods for decoupling structural performance still offer limited ranges for independent regulation, and the design processes tend to be complex. Some methods are not suitable for the promising triply periodic minimal surface (TPMS) structures used in medical implants. Here, we propose an innovative "valve" structure design, incorporating valves with appropriate geometric shapes at suitable positions within the TPMS structure. By varying the valve parameters, we achieve independent regulation (with the highest value reaching up to 6.71-fold.) of structural permeability without affecting structural stiffness (limited to a 2 % variation). Using the proposed strategy, samples with varying parameters were designed for simulation and experimental analysis. The results demonstrate the effectiveness of the proposed strategy in decoupling structural stiffness and permeability. A case study shows the design's simplicity and efficiency in structural reverse design and performance regulation. This strategy has the potential to be applied to a broader range of porous lattice structures, advancing multi-functional lattice structure design.