Integrative design, build, test approach for biomedical devices with lattice structures

Advances in 3D printing are enabling new rapid prototyping strategies for complex structures, such as mechanically efficient tissue scaffolds. Here, we have developed an integrated methodology with Design, Build, and Test phases to characterize beam-based lattices for bone tissue engineering. Lattices were designed with 50% and 70% porosity with beam diameters of 0.4mm to 1.0mm fabricated with polyjet printing. Build accuracy was validated with microscopy that demonstrated overall lattice dimensions were at most 0.2mm different from design and beam diameters were at most 0.15mm different. Quasi-static compression testing showed lattice elastic moduli ranged from 28MPa to 180MPa and decreased with higher lattice porosity but increased with larger beam diameter sizes. Scaffold cages for vertebral bone fusion were prototyped using 50% and 70% porous lattices with 0.8mm diameter beams with added central voids for improved nutrient transport, reinforced shells for increased mechanics, or both. Cage stiffnesses ranged from 1.7kN/mm to 7.2kN/mm and suggests the strongest cage prototypes are suitable for carrying typical spinal loads of up to 1.65kN. The study demonstrates the value in using integrated rapid prototyping approaches for characterizing complex structures and designing novel biomedical devices.