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Microchannels have applications in microfluidic devices, patterns for micromolding, and even flexible electronic devices. Three-dimensional (3D) printing presents a promising alternative manufacturing route for these microchannels due to the technology's relative speed and the design freedom it affords its users. However, the roughness of 3D printed surfaces can significantly influence flow dynamics inside of a microchannel. In this work, open microchannels are fabricated using four different 3D printing techniques: fused deposition modeling (FDM), stereolithography (SLA), selective laser sintering, and multi jet modeling. Microchannels printed with each technology are evaluated with respect to their surface roughness, morphology, and how conducive they are to spontaneous capillary filling. Based on this initial assessment, microchannels printed with FDM and SLA are chosen as models to study spontaneous, capillary-driven flow dynamics in 3D printed microchannels. Flow dynamics are investigated over short (∼10-3 s), intermediate (∼1 s), and long (∼102 s) time scales. Surface roughness causes a start-stop motion down the channel due to contact line pinning, while the cross-sectional shape imparted onto the channels during the printing process is shown to reduce the expected filling velocity. A significant delay in the onset of Lucas-Washburn dynamics (a long-time equilibrium state where meniscus position advances proportionally to the square root of time) is also observed. Flow dynamics are assessed as a function of printing technology, print orientation, channel dimensions, and liquid properties. This study provides the first in-depth investigation of the effect of 3D printing on microchannel flow dynamics as well as a set of rules on how to account for these effects in practice. The extension of these effects to closed microchannels and microchannels fabricated with other 3D printing technologies is also discussed.
Bibliographical noteFunding Information:
The authors would like to thank the industrial supporters of the Coating Process Fundamentals Program (CPFP) of the Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME) for supporting this research. This work was also supported by funding through MnDRIVE at the University of Minnesota. The authors also extend their gratitude to Wieslaw Suszynski for high speed video assistance, Yan Wu for some SEM imaging, Satish Kumar for helpful discussions, and Luke Rodgers and Brian Sabart at Stratasys for printing microchannels with multi jet modeling. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC program, and the Minnesota Nano Center, which receives partial support from the NSF through the NNCI program.
© 2017 American Chemical Society.
Copyright 2018 Elsevier B.V., All rights reserved.
How much support was provided by MRSEC?
Reporting period for MRSEC
- Period 4
PubMed: MeSH publication types
- Journal Article
- Research Support, U.S. Gov't, Non-P.H.S.
- Research Support, Non-U.S. Gov't