Fiber Bridging during Melt Electrowriting of Poly(ε-Caprolactone) and the Influence of Fiber Diameter and Wall Height

Melt electrowriting (MEW) is a direct-writing technology for small diameter fibers; however, due to electrostatic attraction, the technique is restricted in how close these microfibers can be positioned on the collector. Here, the minimum interfiber distance between parallel poly(epsilon-caprolactone) MEW microfibers is determined for different fiber diameters and number of layers on noncoated and star-shaped poly(ethylene oxide-stat-propylene oxide) (sP(EO-stat-PO))-coated glass coverslips. The effect of the fiber diameter, the number of fiber layers, and shape of turning loops affect precision and the minimum interfiber distance. Single fibers with diameter of 5, 10, and 15 mu m have a minimum interfiber distance without fiber bridging of 33 +/- 2.7, 54 +/- 2.2, and 62 +/- 2.7 mu m, respectively. Increasing the number of layers to ten increases this minimum interfiber distance approximately twofold to 60 +/- 3.5, 97 +/- 4.5, and 102 +/- 2.7 mu m for the increasing fiber diameters. The sP(EO-stat-PO) slightly increases the minimum interfiber distance for the 15 mu m diameter group only, with spacing for the 5 and 10 mu m fibers unaffected by the coating. Identifying and determining the fabrication limits for MEW is highly instructional for users working and designing scaffolds with this technology.

Automated summary

The study investigates the minimum interfiber distance of melt electrowritten microfibers on the collector, finding that fiber diameter, number of layers, and shape of turning loops affect precision and spacing. Increasing the number of layers can double the minimum interfiber distance, while coating only affects larger diameter fibers.