High-resolution dual-scale scaffolds via stable-jet dual-spinneret melt electrowriting

In tissue engineering, scaffolds are designed to facilitate cell adhesion, promote proliferation, and guide tissue organization. Melt electrowriting (MEW), an advanced high-resolution additive manufacturing technique, enables precise control over fiber diameter and pore architecture. However, scaffolds fabricated with ultrafine fibers often suffer from insufficient mechanical strength, which limits their practical application. In this study, a dual-spinneret MEW system was developed to enable on-demand switching between fibers of different diameters under continuous and stable jet conditions, allowing the fabrication of hierarchical dual-scale scaffolds from medical-grade poly(ε-caprolactone) (PCL). Mechanically supportive thick fibers (∼67 μm) were integrated with high-resolution thin fibers (∼9 μm), achieving a synergistic balance between load-bearing capability and well-defined topographical cues. Notably, the diameters of the mechanically reinforcing thick fibers are substantially smaller than those produced by conventional fused deposition modeling (FDM) (∼250 μm), thereby minimizing potential interference with cell migration. The resulting scaffolds exhibit enhanced structural stability together with pronounced cell alignment guided by the precisely defined fiber architecture. This work establishes a robust MEW-based manufacturing strategy for constructing mechanically reliable, hierarchically structured scaffolds with high geometric fidelity, expanding the design space of micro-architected materials for tissue engineering applications.