Analytical interpretation of microscale fiber deviation in designing for polymer melt electrohydrodynamic-based additive manufacturing

Abstract

Aided by translational material collection, melt electrowriting is an additive electrohydrodynamic-based materials processing technique capable of fabricating fibrous 3D structured materials with customizable microscale architectures suitable for spatially defined tissue models. An inherent phenomenon of the melt electrowriting process is the characteristic jet lag, which results in spatial differences between the nozzle position ( np ) and the jet contact point ( cp ). Moreover, cp does not deterministically follow the np trajectory when the movement of np relative to the collector is directionally altered. Instead, fiber deviation related to the toolpath deteriorates the printing accuracy and is ubiquitous for curly fiber printing. In order to address this bottleneck, an analytical construct informed by fiber placement prediction and control is advanced. Specifically, by way of vector analysis and differential geometry, the position and speed relationships between np and cp are found to be governed by position- and speed-matching equations. Representations of these equations can be elaborated into the specific cases of straight and steady curly fiber printing, which are investigated and verified herein. Finally, the real-time identification of cp as well as dynamic control of translational stage speed are identified as critical steps towards reliable implementation of the toolpath design in curly fiber printing.