Inertial microfluidics has emerged recently as a promising tool for high-throughput manipulation of particles and cells for a wide range of flow cytometric tasks including cell separation/filtration, cell counting, and mechanical phenotyping. Inertial focusing is profoundly reliant on the cross-sectional shape of channel and its impacts on not only the shear field but also the wall-effect lift force near the wall region. In this study, particle focusing dynamics inside trapezoidal straight microchannels was first studied systematically for a broad range of channel Re number (20 < Re < 800). The altered axial velocity profile and consequently new shear force arrangement led to a cross-lateral movement of equilibration toward the longer side wall when the rectangular straight channel was changed to a trapezoid; however, the lateral focusing started to move backward toward the middle and the shorter side wall, depending on particle clogging ratio, channel aspect ratio, and slope of slanted wall, as the channel Reynolds number further increased (Re > 50). Remarkably, an almost complete transition of major focusing from the longer side wall to the shorter side wall was found for large-sized particles of clogging ratio K ~ 0.9 (K = a/Hmin) when Re increased noticeably to ~ 650. Finally, based on our findings, a trapezoidal straight channel along with a bifurcation was designed and applied for continuous filtration of a broad range of particle size (0.3 < K < 1) exiting through the longer wall outlet with ~ 99% efficiency (Re < 100).
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The first author would like to thank the SINGA scholarship sponsorship by A*STAR graduate academy, Singapore. This work was performed (in part) at the NSW and South Australian node of the Australian National Fabrication Facility under the National Collaborative Research Infrastructure Strategy to provide nano- and micro-fabrication facilities for Australia’s researchers. M.E.W. would like to acknowledge the support of the Australian Research Council through Discovery Project Grants (DP170103704 and DP180103003) and the National Health and Medical Research Council through the Careered Development Fellowship (APP1143377).
Feng J, Hu HH, Joseph DD (1994) Direct simulation of initial value problems for the motion of solid bodies in a Newtonian fluid Part 1. Sedimentation. J Fluid Mech 261:95–134CrossRefzbMATHGoogle Scholar
Guan G, Wu L, Bhagat AA, Li Z, Chen PCY (2013) Spiral microchannel with rectangular and trapezoidal cross-sections for size based particle separation. Sci Rep 3:1495CrossRefGoogle Scholar
Ho B, Leal L (1974) Inertial migration of rigid spheres in two-dimensional unidirectional flows. J Fluid Mech 65:365CrossRefzbMATHGoogle Scholar
Sim TS, Kwon K, Park JC, Lee JG, Jung HI (2011) Multistage-multiorifice flow fractionation (MS-MOFF): continuous size-based separation of microspheres using multiple series of contraction/expansion microchannels. Lab Chip 11:93–99. https://doi.org/10.1039/c0lc00109kCrossRefGoogle Scholar
Situma C, Hashimoto M, Soper SA (2006) Merging microfluidics with microarray-based bioassays. Biomol Eng 23:213–231CrossRefGoogle Scholar
Sudarsan AP, Ugaz VM (2006) Fluid mixing in planar spiral microchannels. Lab Chip 6:74–82CrossRefGoogle Scholar
Vasseur P, Cox R (1976) The lateral migration of a spherical particle in two-dimensional shear flows. J Fluid Mech 78:385CrossRefzbMATHGoogle Scholar
Voldman J (2006) Electrical forces for microscale cell manipulation. Annu Rev Biomed Eng 8:425CrossRefGoogle Scholar
Wang L, Li PC (2011) Microfluidic DNA microarray analysis: a review. Anal Chim Acta 687:12–27CrossRefGoogle Scholar
Warkiani ME, Lou C-P, Gong H-Q (2011) Fabrication and characterization of a microporous polymeric micro-filter for isolation of Cryptosporidium parvum oocysts. J Micromech Microeng 21:035002CrossRefGoogle Scholar
Warkiani ME, Lou C-P, Liu H-B, Gong H-Q (2012) A high-flux isopore micro-fabricated membrane for effective concentration and recovering of waterborne pathogens. Biomed Microdevice 14:669–677CrossRefGoogle Scholar