Design and Mechanical Testing of 3D Printed Hierarchical Lattices Using Biocompatible Stereolithography

• Main Authors: Md Moniruzzaman, Christopher O'Neal, Ariful Bhuiyan, Paul F. Egan
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Designs
• Subjects: mechanics; 3D printing; additive manufacturing; stereolithography; lattices; metamaterials
• Online Access: https://www.mdpi.com/2411-9660/4/3/22

Emerging 3D printing technologies are enabling the rapid fabrication of complex designs with favorable properties such as mechanically efficient lattices for biomedical applications. However, there is a lack of biocompatible materials suitable for printing complex lattices constructed from beam-based unit cells. Here, we investigate the design and mechanics of biocompatible lattices fabricated with cost-effective stereolithography. Mechanical testing experiments include material characterization, lattices rescaled with differing unit cell numbers, topology alterations, and hierarchy. Lattices were consistently printed with 5% to 10% lower porosity than intended. Elastic moduli for 70% porous body-centered cube topologies ranged from 360 MPa to 135 MPa, with lattices having decreased elastic moduli as unit cell number increased. Elastic moduli ranged from 101 MPa to 260 MPa based on unit cell topology, with increased elastic moduli when a greater proportion of beams were aligned with the loading direction. Hierarchy provided large pores for improved nutrient transport and minimally decreased lattice elastic moduli for a fabricated tissue scaffold lattice with 7.72 kN/mm stiffness that is suitable for bone fusion. Results demonstrate the mechanical feasibility of biocompatible stereolithography and provide a basis for future investigations of lattice building blocks for diverse 3D printed designs.