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Updated: Jun 16, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
Passive regulation of volume-flow ratio for microfluidic streams with different hydrophilicity and viscosity
Sung-Jin Kim1, Yong Taik Lim, Haesik Yang
1BioMEMS Group, Electronics and Telecommunications Research Institute, Daejeon, Korea.
Abstract:
Biochemical solutions have a wide range of hydrophilicity (contact angle and surface tension) and viscosity. A critical challenge is that microfluidic systems typically need expensive or complex pumps to control the various parallel biochemical streams. In this study, without using any pumps, we present a simple scheme that controls the ratio of the volumetric flow rate (VFR) of the parallel streams that have highly different hydrophilicity and viscosity. We accomplish this process by using capillarity to drive and merge two streams, and by regulating relative flow resistance to control the VFR ratio. Our results will significantly simplify the control of the VFR ratio for the various biochemical solutions that are used in microfluidic applications.
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