Fibre pulsing during melt electrospinning writing

Abstract

Additive manufacturing with electrohydrodynamic direct writing is a promising approach for the production of polymeric microscale objects. In this study we investigate the stability of one such process, melt electrospinning writing, to maintain accurate placement of the deposited fibre throughout the entire print. The influence of acceleration voltage and feeding pressure on the deposited poly(ε-caprolactone) fibre homogeneity is described, and how this affects the variable lag of the jet drawn by the collector movement. Three classes of diameter instabilities were observed that led to poor printing quality: (1) temporary pulsing, (2) continuous pulsing, and (3) regular long bead defects. No breakup of the electrified jet was observed for any of the experiments. A simple approach is presented for the melt electrospinning user to evaluate fibre writing integrity, and adjust the processing parameters accordingly to achieve reproducible and constant diameter fibres.

Melt electrowriting of electroactive poly(vinylidene difluoride) fibers

“…The results of these analyses for fiber diameter are presented in Figs and . 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 …”

“…The upper fiber trace can be seen crossing paths forming over the lower fiber trace indicating some viscous properties upon landing on the collector. Such fibers could be deposited quite readily with good accuracy with minimal change in fiber diameter due to fiber pulsing …”

“…In this study, we employ melt electrowriting (MEW), which is distinct from electrospinning in that electrical instabilities are suppressed to precisely place fibers but are sufficient to maintain a fluid column from breaking at low flow rates . When the collector speed for MEW matches the jet speed, widely termed the critical translation speed, this fluid column can be directly written as a linear fiber …”

Melt Electrowriting of Thermoplastic Elastomers

“…These steep increases of η melt are assumed to result from back reactions forming isocyanates moieties and subsequent cross‐linking at higher temperatures. No fibre pulsing of the electrified jet was observed at the optimal conditions, determined by visualization of the print edges as previously described …”

Rheological Characterization of Biomaterials Directs Additive Manufacturing of Strontium‐Substituted Bioactive Glass/Polycaprolactone Microfibers

“…Melt electrowriting (MEW) has been established as a versatile additive manufacturing technique for biofabrication, tissue engineering, and regenerative medicine research . MEW is a specialized electrospinning platform which creates micro‐ and nano‐scale fibers usually collected as mats with high levels of control over fiber size, porosity, and fiber laydown patterns . A high potential difference between the nozzle and collector plate instigates the formation of a “Taylor cone” at the base of the nozzle through complex interactions between the polymer and strong electric field, drawing out micron‐scale fibers.…”