Dimension‐Based Design of Melt Electrowritten Scaffolds

Abstract

The electrohydrodynamic stabilization of direct-written fluid jets is explored to design and manufacture tissue engineering scaffolds based on their desired fiber dimensions. It is demonstrated that melt electrowriting can fabricate a full spectrum of various fibers with discrete diameters (2-50 µm) using a single nozzle. This change in fiber diameter is digitally controlled by combining the mass flow rate to the nozzle with collector speed variations without changing the applied voltage. The greatest spectrum of fiber diameters was achieved by the simultaneous alteration of those parameters during printing. The highest placement accuracy could be achieved when maintaining the collector speed slightly above the critical translation speed. This permits the fabrication of medical-grade poly(ε-caprolactone) into complex multimodal and multiphasic scaffolds, using a single nozzle in a single print. This ability to control fiber diameter during printing opens new design opportunities for accurate scaffold fabrication for biomedical applications.

Melt electrowriting of electroactive poly(vinylidene difluoride) fibers

“…The observed reduction in the fiber diameter with increased collection speed is due to the mechanical elongation of the electrified jet . The reduction in fiber diameter with collector speed is in agreement with other studies involving PCL, poly(hydroxymethyl glycolide‐ co ‐ϵ‐caprolactone) and PP …”

“…Between each pressure transition, a stabilization routine was performed whereby a deposition of fibers was electrowritten off the collector slide for a 3 min duration. This was done to mitigate some of the instability that is commonly seen when transitioning to a different applied pressure . To investigate potential effects of thermal degradation, each set of two slides (corresponding to one parameter sweep) was printed at t = 0, 0.5, 1.0, 2.0, 4.0, 8.0 and 10.0 h of heating, with the molten polymer maintained at a constant printing temperature even when idle.…”

“…22 Figure 4 reveals the trends in average fiber diameter that are consistent with previous studies on MEW, with different polymers such as PCL, PP and poly(2-ethyl-2-oxazoline). 21,33,42 For example, increasing the applied N 2 pressure increases the diameter of the collected fiber ( Fig. 4) while increasing the collector speed reduces the diameter.…”

“…This was done to mitigate some of the instability that is commonly seen when transitioning to a different applied pressure. 33 To investigate potential effects of thermal degradation, each set of two slides (corresponding to one parameter sweep) was printed at t = 0, 0.5, 1.0, 2.0, 4.0, 8.0 and 10.0 h of heating, with the molten polymer maintained at a constant printing temperature even when idle. Each time experiment was performed in triplicate.…”

Biologically Inspired Scaffolds for Heart Valve Tissue Engineering via Melt Electrowriting

“…Melt electrowriting (MEW) is an emerging manufacturing technique that enables the fabrication of solvent‐free, highly organized fibrous scaffolds with micrometric features by merging principles of electrospinning and additive manufacturing . Therefore, it has the potential to overcome the limitations of the currently employed fabrication techniques by a predefined and preprogrammed fiber deposition .…”