Hollow-Fiber Melt Electrowriting Using a 3D-Printed Coaxial Nozzle

Herein, a 3D-printed nozzle designed for the single-step fabrication of melt electrowritten hollow fibers is introduced. To achieve this, selective laser melting (SLM) is used to fabricate the outer part of the coaxial nozzle (800 μm inner diameter) from Ti6Al4V, into which a conventional nozzle (250 μm inner diameter) is inserted. Several iterations of coaxial nozzle design result in a well-aligned inner core nozzle that delivers air into the Taylor cone of medical-grade poly(ε-caprolactone) (PCL). Air from this bubble forms the hollow part of the fiber while the PCL shell solidifies as the shell. The smallest PCL fibers have an approximate outside diameter of 10 μm and a lumen of 6 μm, making this a promising one-step technique for small diameter hollow fiber fabrication.