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Proceedings Paper

Multiple-stream flow and mixing of dissimilar polymeric solutions in abrupt microfluidic contraction/expansion geometries
Author(s): Hiong Yap Gan; Yee Cheong Lam
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Paper Abstract

In simple microfluidic contraction/expansion geometry, even a dilute polymeric solution is able to exhibit large upstream corner vortices and unstable entry flow patterns at high enough deformation rate (Deborah Number > 200). We have previously demonstrated a similar concept on multiple-stream flow of dissimilar viscoelastic solutions in planar microdevices containing abrupt contraction. Using the same test-vehicle, here we attempt to show that the elasticity ratio between two solutions plays an important role in entire flow kinematics (both upstream and downstream of a contraction) and thus the enhanced mixing of the two solutions. That is the upstream's stretching dynamics induced by the converging flow and the downstream's relaxation events are not exclusively responsible for the multi-stream flow kinematics but the elasticity ratio is also equally important. In this paper, the necessity of elasticity ratio for convective flow instability and the associated enhanced mixing were demonstrated experimentally. Our results show that the magnitude of the viscoelastically induced flow instability can be directly correlated to the energy discontinuity at the stream-stream interfaces at downstream of a contraction. These findings lay the foundation for optimizing the desired mixing quality via viscoelastic flow instability with negligible diffusion and inertial effects. This type of mixing can be achieved over short mixing length at relatively fast flow velocities (~101 mm/s) and is postulated to be easily integrated into μTAS platforms due to its simple design.

Paper Details

Date Published: 14 February 2012
PDF: 8 pages
Proc. SPIE 8251, Microfluidics, BioMEMS, and Medical Microsystems X, 82510U (14 February 2012); doi: 10.1117/12.912950
Show Author Affiliations
Hiong Yap Gan, A*STAR Singapore Institute of Manufacturing Technology (Singapore)
Yee Cheong Lam, Nanyang Technological Univ. (Singapore)

Published in SPIE Proceedings Vol. 8251:
Microfluidics, BioMEMS, and Medical Microsystems X
Holger Becker; Bonnie L. Gray, Editor(s)

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