Bio-inspired design, mechanical and mass-transport characterizations of orthotropic TPMS-based scaffold

Abstract

To obtain porous scaffolds with bionic anisotropic structures similar to human bone, the orthotropic triply periodic minimal surface (TPMS)-based structures were proposed in this study. The orthotropic Schoen’s I-WP (AP) and orthotropic Gyroid (AG) were designed based on isotropic I-WP (IP) and isotropic Gyroid (IG). The four scaffolds with 70% porosity were fabricated by electron beam melting, and then were scanned by microcomputer tomography to evaluate their manufacturability. The anisotropic degrees of elastic properties of the scaffolds were calculated using the homogenization approach. Compression test along the three orthogonal directions was conducted on the scaffolds to analyze their mechanical properties. Computational fluid dynamics was performed to the scaffolds along the three orthotropic directions to characterize their mass transport properties. Results show that AP and AG possess irregular pores and perform well in manufacturability compared with IP and IG. Similar to human bone, AP and AG exhibit orthotropic mechanical properties and mass transport performances. Furthermore, the elastic modulus ratio of AG along the three orthogonal directions is close to the value of cancellous bone. The designed scaffolds are advantageous for their bionic mechanical and mass transport properties of human bone and can be the proper candidates in bone graft surgery.