Modular-based gradient scaffold design and experimental studies for tissue engineering: enabling customized structures and mechanical properties

In tissue engineering, scaffolds must be designed or tailored with the structures and mechanical behavior appropriate for repairing the defective tissue, which, however, remains unachievable. In this paper, we present a modular scaffold design method and illustrate its effectiveness by using three basic units with different structures and porosities and then rigorously stacking them into six scaffold designs of varying porosities or gradients and thus mechanical behaviors. Samples of designed scaffolds were prepared by the selective laser melting (SLM) technique using Al-Si10-Mg powder and the mechanical properties were examined by compressive testing. In parallel, the mechanical behavior of scaffolds was simulated based on the Johnson–Cook model. Furthermore, a performance optimization strategy was developed based on genetic algorithm, which allows one to design scaffolds from basic units with tailored mechanical properties and porosity. Our results show that among the examined six scaffolds, the triangular modular design has strong load-bearing capacity and energy absorption capacity, and the hexagonal modular design has a good deformation capacity with high energy absorption efficiency. The deformation behavior of the modular design with a radial gradient of porosity and the one with a local-varying porosity show that shear fracture occurs at 45° to the loading direction. Also, the elastic modulus and porosity of the scaffolds designed using the developed optimization strategy are close. to the targeted values. Taken together, the present study illustrates the modular design method allows one to design scaffolds with tailored structures and mechanical properties, representing a big advance for developing scaffolds in tissue engineering.