Design, fabrication, and characterization of tubular scaffolds by way of a melt electrowriting process

Melt electrowriting (MEW) has emerged as a reliable additive manufacturing method for the fabrication of microscale fibrous tissue scaffolds. In order to expand the application scope of MEW, a controllable rotational mandrel is adapted as the collector for the fabrication of tubular scaffolds. Herein, the fundamental mathematical relationships among the tubular scaffold design parameters (winding angle (αw), number of pivot points (ndes), length of the tubular scaffold (L), and mandrel radius (R)) are established to enable various types of homogeneous and heterogeneous tubular scaffold designs. One type is the single-segment scaffold with a homogeneous 4-sided pore morphology. The other type is the multi-segment scaffold, which can possess multi-sided pores and spatially heterogeneous structures. Then, the printed scaffolds are structurally and mechanically evaluated. On the one hand, the scaffold design parameters (ndes, N and αw) are observed to have a negligible effect on the structural outcomes (αw, L, and fiber diameter (df)). On the other hand, increments in ndes and layer number (N), along with decrements in αw, are observed to yield enhanced mechanical outcomes. Lastly, the process parameter effects of collector speed on the tubular scaffold printing outcomes are investigated for the first time, which elaborate the most favorable conditions for obtaining highly-ordered scaffolds. Specifically, an increase in the collector speed parameter is accompanied by an observed increase in jet lag, leading to deterioration in the printing accuracy of tubular scaffolds.