A Fundamental Study of Charge Effects on Melt Electrowritten Polymer Fibers

Houzhu Ding, Kai Cao, Fucheng Zhang, William Boettcher, Robert C. Chang

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

Melt electrowriting (MEW) is an electrohydrodynamics (EHD)-based additive manufacturing paradigm for printing microscale fibers. Although models for charge transport during EHD printing have been described, significant challenges arise from the in-process charge dynamics in MEW process, which limits the achievable print resolution. This paper advances a methodology to analyze the effects of charge dynamics on the MEW-printed structure resolution. First, fibers printed with an oscillating toolpath exhibit two distinct alignment patterns with constituent fibers either successively overlapping along the toolpath or diverging into individual fibers without apparent overlap on conductive and non-conductive substrates, respectively, pointing to the existence of inter-fiber charge phenomena. Next, a set of straight fibers are printed on two types of substrates to investigate the relationship between the prescribed inter-fiber distance (set Sf) and measured Sf. Both repulsion (measured Sf > set Sf) and attraction (measured Sf < set Sf) are observed. Moreover, a mathematical model based on line-point charge interactions is advanced to explain the fiber attraction-repulsion phenomenon. Finally, residual charge measurements with a customized Faraday Cup reveal that printed scaffolds on conductive and non-conductive substrates are negatively and positively charged for residual charge, respectively.

Original languageEnglish
Article number107857
JournalMaterials and Design
Volume178
DOIs
StatePublished - 15 Sep 2019

Keywords

  • Melt electrowriting
  • Residual charge
  • Substrate conductivity

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