Abstract
Soft and hard micromachining techniques used to develop microfluidic devices can yield microchannels of many different cross-sectional profiles. For semi-circular microchannels, these techniques often produce only partialsemicircular (PSC) cross-sections. This study investigated fully developed laminar flow in PSC microchannels as a function of a circularity index, κ, defined as the ratio of the radiuses along the curved and flat surfaces of the PSC profile. A correction factor, K, to the Hagen-Poiseuille relation was determined and was well-fitted by the power-law relationship K=5.299/κ2.56. Actual correction factors were compared to estimates based on several hydraulic models for flow in microchannels of arbitrary cross-section, as well as the half-ellipsoid cross-section. The level of wall shear stress, when normalized by the pressure drop per unit length, increased approximately linearly with increase in the circularity index, κ.
Highlights
This study investigated fully developed laminar flow in partial semi-circular (PSC) microchannels as a function of a circularity index, defined as the ratio of the radiuses along the curved and flat surfaces of the PSC profile
The trend toward miniaturization that has been driven by advances in fabrication processes derived from microelectromechanical systems (MEMs) and other microsystem technologies has led to microfluidic devices for use in numerous chemical, biological and medical applications
The geometry and geometrical parameters for the partial semi-circular (PSC) microchannel are shown in Figure 2(a) in the x, y plane, where z is the direction of flow
Summary
The trend toward miniaturization that has been driven by advances in fabrication processes derived from microelectromechanical systems (MEMs) and other microsystem technologies has led to microfluidic devices for use in numerous chemical, biological and medical applications. Recent studies that have developed microchannels with semi-circular profiles include an analysis of shear stress effects on endothelial cells in curved microvessels [5], the evaluation of micromachined flow cytometers with integrated optics [6,7], the creation of a novel magnetohydrodynamic micropump [8], and studies of microfluidic devices for capillary electrophoresis [9]. Oosterbroek [11] used analytical and approximation techniques to determine or estimate the velocity profiles in different microchannel geometries. The results of our study on fully-developed flow in PSC microchannels are compared and evaluated against the theories described above in these recent studies
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