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[Conference Article]Investigation of the capillary flow through open surface microfluidic structures


The passive nature of capillary microfluidics for pumping and actuation of fluids is attractive for many applications including point of care medical diagnostics. For such applications, there is often the need to spot dried chemical reagents in the bottom of microfluidic channels after device fabrication; it is often more practical to have open surface devices (i.e., without a cover or lid). However, the dynamics of capillary driven flow in open surface devices have not been well studied for many geometries of interest. In this paper, we investigate capillary flow in an open surface microchannel with a backward facing step.

An analytical model is developed to calculate the capillary pressure as the liquid-vapor interface traverses a backward facing step in an open microchannel. The developed model is validated against results from Surface Evolver liquid-vapor surface simulations and ANSYS Fluent two-phase flow simulations using the volume of fluid approach. Three different aspect ratios (inlet channel height by channel width) were studied. The analytical model shows good agreement with the simulation results from both modeling methods for all geometries. The analytical model is used to derive an expression for the critical aspect ratio (the minimum channel aspect ratio for flow to proceed across the backward facing step) as a function of contact angle. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Ahmed Taher, Liesbet Lagae

KU Leuven (Belgium)

Benjamin Jones, Paolo Fiorini

IMEC (Belgium)

Proc. SPIE 10061, Microfluidics, BioMEMS, and Medical Microsystems XV, 1006108 (February 28, 2017); doi:10.1117/12.2249836

Link: http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2607936

From Conference Volume 10061

  • Microfluidics, BioMEMS, and Medical Microsystems XV

  • Bonnie L. Gray; Holger Becker

  • San Francisco, California, United States | January 28, 2017

#microchannels #capillary #simulation #03062017

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