Additive Manufacturing of Bead-Chain-Shaped Scaffolds with AI-Based Process Optimization

Scaffolds are widely recognized as implantable alternatives in the field of tissue engineering. Among various scaffold structures, grid structures are commonly used due to their simple design and ease of fabrication. However, grid structures have a critical demerit of low mechanical stiffness compared to its own mechanical property (used material's compressive stiffness), as the limited contact area between strands prevents effective load distribution. Several structural designs, such as triply periodic minimal surface (TPMS), modified honeycomb, and Kagome structures, have been proposed to improve compressive stiffness. Despite their mechanical advantages, these structures are limited by complex design and manufacturing processes. In this study, we propose a Bead-Chain-Shaped (BCS) scaffold, which maintains the simplicity of grid structures while enhancing compressive stiffness through the printing process alone. To optimize the printing process and enhance fabrication efficiency, we developed an artificial intelligence (AI)-based process optimization model that correlates printing parameters (pressure, printing speed, and delay time) with the resulting geometric accuracy while maintaining the designed geometry, and predicts the optimal printing conditions for the predesigned Bead-Chain-shaped (BCS) geometry. The model was then used to extract these optimal printing conditions, enabling precise dimensional control and improving overall fabrication accuracy of the Bead-Chain-Shaped (BCS) scaffold dimensions. Under the optimized printing conditions, the BCS scaffolds achieved compressive stiffness values of 61.8, 75.9, and 91.6 MPa for BCS 5545, 6040, and 6535, respectively, corresponding to increases of 11.9%, 37.3, and 65.7% compared to the control scaffold (55.3 MPa). Numerical analysis confirmed that compressive stiffness increases as strand-to-strand contact area increases. Furthermore, in vitro cell proliferation assays demonstrated no significant difference in cell proliferation compared to conventional structures (grid-structure scaffold), indicating that the proposed design does not inhibit cellular growth. These results highlight the potential of the proposed Bead-Chain-Shaped (BCS) scaffold as a promising candidate for bone tissue engineering, offering both enhanced mechanical stiffness and fabrication efficiency.