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Title:Multinozzle printheads for 3D printing of viscoelastic inks
Author(s):Kranz, Stephen
Advisor(s):Lewis, Jennifer A.
Department / Program:Materials Science & Engineerng
Discipline:Materials Science & Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):multinozzle
printhead
3D printing
extrusion
fluid modeling
woodpile
Abstract:A high-pressure microfluidic device for 3D extrusion printing of viscoelastic ink was developed. The device was machined out of poly(methylmethacrylate) (PMMA) using a 3-axis CNC mill and contains a bifurcating array of microchannels that split a single stream of ink into 64 streams of equal flow. The device extrudes 64 filaments, each with a square cross section of 200 µm by 200 µm. The device was built to dramatically increase throughput of 3D printed structures. An iterative 1D model was developed that predicts the relative volumetric flow rates of power-law fluids in individual channels of a microfluidic network. The model utilized a modified Hagen-Poiseuille equation and the hydraulic-electric analogy. The model was employed to predict hydraulic resistances of various network designs and to determine the effects of geometric asymetries on the uniformity of extruded filaments. High-pressure microfluidic printheads were developed for 3D printing of viscoelastic inks. These multinozzle arrays were machined out of poly(methylmethacrylate) (PMMA) using a 3-axis CNC mill. Several printhead designs were made, tested, and modeled, including those with bifurcating arrays of microchannels of varying sizes and a plenum design that split a single stream of ink into multiple streams of equal flow yielding devices with 8-, 16-, 64- and 128-nozzles (or outputs). These microfluidic devices were designed to enable (1) high throughput, 3D printing, (2) multimaterial deposition, and (3) parallel printing of arbitrary designs. An iterative 1D model was developed that predicts the relative volumetric flow rates of power-law fluids in individual channels of a microfluidic network. The model utilized a modified Hagen-Poiseuille equation and the hydraulic-electric analogy. The model was employed to predict hydraulic resistances of various network designs and to determine the effects of geometric asymmetries on the uniformity of extruded filaments. The predictions of this simplified 1D model were in good agreement with those made by 3D finite element modeling using COMSOL. Finally, these multinozzle printheads were mounted on a 3-axis motion-controlled printer. Using these multinozzle printheads, multiple ink types were successfully patterned, including an organic wax ink, a photo-curable epoxy, a hydrogel, and two colloidal inks.
Issue Date:2013-08-22
URI:http://hdl.handle.net/2142/45310
Rights Information:Copyright 2013 Stephen Kranz
Date Available in IDEALS:2013-08-22
Date Deposited:2013-08


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