A Decade of Melt Electrowriting

Abstract

Over the past decade, melt electrowriting (MEW) has established the fundamental understanding of processing (and printer) requirements. Iterative work on parametric development and dissemination of this recent additive manufacturing technology has been performed across many systems and polymers (mainly poly-(𝝐-caprolactone)), showing similarities and trends. However, the software and hardware ecosystems of MEW are not mature. Further, due to its multi-parametric nature, MEW can be challenging for laboratories to master. This review intends to provide a unique perspective on the dynamic relationship between MEW processing parameters. Such parameters can be divided into 1) those that affect the polymer flow rate to or 2) from the nozzle, and 3) environmental conditions. The most influential parameters for high-quality printing are applied voltage, applied pressure, collector speed, polymer temperature, nozzle diameter, and the conditions that lead to charge buildup (e.g., relative humidity). Other factors such as ambient temperature, nozzle size, and protrusion, collector temperature and conductivity, and collector distance can all affect the process. Success for MEW printing means fibers fall onto the collector according to their pre-programmed path with predicted fiber diameter. Here, the authors elucidate how the dynamic relationship between these parameters can converge into ideal printing conditions to produce scaffolds.

Improving Infection Resistance in Tissue Engineered Scaffolds for Tensile Applications Using Vancomycin‐Embedded Melt Electrowritten Scaffolds

“…The wavy A geometry has the longest length of fiber to uncrimp during loading (≈2.80 mm of diagonal fibers per 1.25 mm spacing between straight fibers, causing the observed elongated toe region and slower transition to the linear region compared to wavy B geometry that only had a total length of ≈1.50 mm fiber to uncrimp during loading. The larger amplitude of the wavy A fibers resulted in errors due to layer shifting [21,24] which also led to a slight decrease in the elastic modulus (Figure 1F). In contrast, UTS (Figure 1G) and yield strength (Figure 1H) showed a significant increase for both wavy A (>60%) and wavy B (>29%) geometries respectively, indicating superior failure performance of wavy scaffolds.…”

Biointerface Fiber Technology from Electrospinning to Inflight Printing

“…By shortening the tip-to-collector distance to the range of ∼0.5 to 3 mm, NFES could realize fiber printing with a much lower voltage of ∼1 kV (Figure a-i); thus to enable controllable fiber deposition of various patterns. , The chemical and rheological properties of the fiber solutions, such as conductivity, surface tension, boiling point, and viscosity, are crucial parameters that determine the fiber formation. Balancing these parameters and understanding their interplay are the keys to control the fiber morphologies in NFES.…”

Microfibrous Scaffolds Guide Stem Cell Lumenogenesis and Brain Organoid Engineering

“…In this study, we use melt electrospinning writing (MEW), a rapidly growing high-resolution fabrication technology with massive potential for porous tissue engineering scaffolds, to produce centimeter-sized microfibrous scaffolds (Figure 1a). [21,22] Furthermore, we optimize a process workflow for uniform stem cell seeding and EB formation (Figure 1b). We show that the geometric parameters of the scaffold can be tuned to guide the emergence and morphology of lumens and differentiate these geometrically defined EBs into interconnected cerebral organoids.…”