Browsing by Subject "direct-write printing"

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Multimaterial Aerosol Jet Printing of Passive Circuit Elements
(University of Texas at Austin, 2018) Johannes, S.J.; Keicher, D.M.; Lavin, J.M.; Secor, E.B.; Whetten, S.R.; Essien, M.
Recent advances in additive manufacturing technologies present opportunities for rethinking the design and fabrication of electronic components. An area of considerable interest for electronic printing is the production of multi-layered, multi-material passive components. This research focuses on the design and fabrication of a toroidal microinductor using a digital, direct-write printing platform. The toroidal inductor has a three layer design with a dielectric and core material printed in between the lower and upper halves of the conductive coil. The results of this work are discussed, including printer, ink, and processing requirements to successfully print the multi-layer, multi-material component. The inductance of several successful printed devices is measured and compared to predicted values. Overall, the results and lessons of this work provide guidance for future work in this growing field.
Nonlinear and Linearized Gray Box Models of Direct-Write Printing Dynamics
(University of Texas at Austin, 2018) Simeunovic, A.; Hoelzle, D.
Control of material metering in material extrusion based additive manufacturing modalities, such as positive displacement direct-write, is critical for manufacturing accuracy. However, in positive displacement direct-write, transient flows are poorly controlled due to capacitive pressure dynamics - pressure is stored and slowly released over time from the build material and other compliant system elements, negatively impacting flow rate startups and stops. Thus far, modeling of these dynamics has ranged from simplistic, potentially omitting key contributors to the observed phenomena, to highly complex, making usage in control schemes difficult. Here, we present nonlinear and linearized models that seek to both capture the capacitive and nonlinear resistive fluid elements of positive displacement direct-write systems and to pose them as ordinary differential equations for integration into nonlinear and linear control schemes. We validate our theoretical work with experimental flow rate and material measurements across a range of extrusion nozzles and materials to address different feature sizes and diverse applications spanning tissue engineering, electronics fabrication, and food science. As part of this experimental work, we explore the contribution of the bulk system compliance and the build material compliance to these dynamics. We show that all models accurately describe the measured dynamics, facilitating ease of integration into future nonlinear and linear control systems. Additionally, we show that while build material compliance may be nearly entirely reduced through appropriate system design, the compliance from build material alone is significant enough to require feedback control to fully control material delivery.