Decoupling microlattice metamaterial properties through a structural design strategy inspired by the Hall–Petch relation

With the development of structural architectures, the demand for metamaterials with multiphysical characteristics has increased. The relationships between different properties, such as mechanical and mass-transport properties for bone scaffolds, are often mutually conflicting. Consequently, the optimization of these properties for metamaterials structured on the micro- to macroscale is challenging. In this study, inspired by the Hall–Petch relation, which indicates how one can independently tailor the strength and mass, we use a diamond configuration to construct microlattice metamaterials with decoupled mechanical and mass-transport properties to cater to artificial bone scaffolds. The elasticity and permeability are synchronously optimized using simple scaling laws. The results of compression experiments and transportation calculations demonstrate the promising performance of microlattices with an aspect ratio of 1 and at least 4 unit cells in the array direction. Furthermore, hierarchical microlattice metamaterials partitioned into spongy and compact zones are designed for bone scaffold applications. The proposed approach provides an innovative framework for developing multi-physics metamaterials for widespread engineering applications.