A Deeper Insight into the Influence of the Electric Field Strength When Melt‐Electrowriting on Non‐Planar Surfaces

Abstract

Defined structures for tissue engineering can be achieved by a variety of techniques, one of which includes melt-electrowriting (MEW), a technology that deposits spatially defined microfibers of a molten polymer across an electric field. In this study, the authors investigate how to microfabricate biomaterial-meshes using MEW to non-planar surfaces that will have more applicability to anatomical structures. By modeling the electric field strength associated with MEW, it is found that incorporation of a non-conductive 3D printed mould on the conductive collector plate offers the ability to accurately print patterns on non-planar surfaces successfully. Importantly, if the applied voltage at the nozzle or collector plate is kept constant in the MEW process, the electrostatic behavior of the deposited polymer, and the electric field strength between the collector and nozzle (which is greatest at the nozzle) has the greatest impact on the accuracy of fiber patterning and stacking. Consequently, controlled fiber deposition is exhibited, provided that a constant voltage and a constant vertical distance between the nozzle and the mould are maintained. Overall, this study establishes the groundwork to support further developments in MEW technologies, from flat to anatomically relevant 3D structures in the fields of regenerative medicine and biofabrication.

Recent advances in melt electro writing for tissue engineering for 3D printing of microporous scaffolds for tissue engineering

“…For precise fabrication of curved contour meshes on a nonplanar collector, Saha et al characterized the influence of nozzle distance and strength of the electrical field for curved surfaces. He placed a non-conductive polylactid acid dome on a flat conductive collector to investigate fiber deposition properties and could show, that an accurate fiber deposition is achievable by maintaining a constant electrical field through a constant vertical distance between nozzle and collector ( Saha et al, 2021 ).…”

Electrohydrodynamic 3D Printing of Aqueous Solutions

“…[127] Conversely, a non-conductive substrate increases the charge accumulation and induces a repulsion effect on fibers "in-flight." [155] Few works have explored the effect of substrate conductivity on aqueous EW, and even less the use of dielectric substrates, such us polymers. The obtained result suggests that more conductive aqueous solutions are better operated with insulating initiators (e.g., glass slides, or polymeric pre-printed grids), while insulating solutions (polymer melts) perform better with conductive substrates.…”

“…Over it, non‐conductive glass, conductive coating over the non‐conductive glass, semi‐conducting (e.g., silica), and conducting substrates are used for EW. The few experimental works exploring the collector effect with molten dielectric polymers suggest that a higher substrate conductivity promotes the release of entrapped charges through physical contact or corona discharge, leading to deposited fibers polarization, and attraction effect to oppositely charged fibers “in‐flight.” [ 127 ] Conversely, a non‐conductive substrate increases the charge accumulation and induces a repulsion effect on fibers “in‐flight.” [ 155 ] Few works have explored the effect of substrate conductivity on aqueous EW, and even less the use of dielectric substrates, such us polymers. The obtained result suggests that more conductive aqueous solutions are better operated with insulating initiators (e.g., glass slides, or polymeric pre‐printed grids), while insulating solutions (polymer melts) perform better with conductive substrates.…”

Melt Electrowriting of Poly(dioxanone) Filament Using a Multi‐Axis Robot

“…A mandrel collector is used for MEW tubes, while several reported placing an object (i.e., a dome, ramp) onto an X-Y collector. [18,19] Achieving a higher degree of freedom through a multi-axis robot is necessary, however, to accurately direct-write onto a steeply curved surface using MEW. [18] Electrical fields will affect the deposition of fibers and in this study, a multi-axis robot was used to maintain this constant electric field onto a dome collector.…”