Single line particle focusing induced by viscoelasticity of the suspending liquid: theory, experiments and simulations to design a micropipe flow-focuser

D’Avino, Gaetano; Romeo, Giovanni; Villone, Massimiliano M.; Greco, Francesco; Netti, Paolo A.; Maffettone, Pier Luca

doi:10.1039/c2lc21154h

Cited by 186 publications

(247 citation statements)

References 23 publications

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“…Under the assumption of zero Reynolds number and small blockage ratio, Ho & Leal (1976) showed that a lateral force, originating from the normal stress differences, drives the particle towards the lower-shear region in a second-order fluid. This conclusion has been verified in other experiments and simulations, where particles move to the central axis of a circular tube (Tehrani 1996;D'Avino et al 2012;Romeo et al 2013;Kang et al 2014) and to both centreline and corners in a rectangular channel (Yang et al 2011;Leshansky et al 2007). Based on simulations of the Giesekus and Phan Thien-Tanner constitutive equations, Villone et al (2011, 2013) and D'Avino et al (2012 observed bistable dynamics of particles in shear-thinning fluids, i.e.…”

Section: Introductionsupporting

confidence: 51%

Dynamics of particle migration in channel flow of viscoelastic fluids

2015

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The migration of a sphere in the pressure-driven channel flow of a viscoelastic fluid is studied numerically. The effects of inertia, elasticity, shear-thinning viscosity, secondary flows and the blockage ratio are considered by conducting fully resolved direct numerical simulations over a wide range of parameters. In a Newtonian fluid in the presence of inertial effects, the particle moves away from the channel centreline. The elastic effects, however, drive the particle towards the channel centreline. The equilibrium position depends on the interplay between the elastic and inertial effects. Particle focusing at the centreline occurs in flows with strong elasticity and weak inertia. Both shear-thinning effects and secondary flows tend to move the particle away from the channel centreline. The effect is more pronounced as inertia and elasticity effects increase. A scaling analysis is used to explain these different effects. Besides the particle migration, particle-induced fluid transport and particle migration during flow start-up are also considered. Inertia effects, shear-thinning behaviour, and secondary flows are all found to enhance the effective fluid transport normal to the flow direction. Due to the oscillation in fluid velocity and strong normal stress differences that develop during flow start-up, the particle has a larger transient migration velocity, which may be potentially used to accelerate the particle-focusing.

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Section: Introductionsupporting

confidence: 51%

Dynamics of particle migration in channel flow of viscoelastic fluids

2015

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“…The correlation between the particle defocusing and shear thinning is consistent with existing experimental and numerical observations showing that the shear thinning effect always drive the particle closer to the wall in viscoelastic fluids. 47,[52][53][54] Fluids with high viscosities are also undesirable for particle manipulation, since throughput is limited by high pressure drop and multiple focusing pattern will exist over a wide range of flow rates due to low Re. In the 5 wt % PVP solution with high viscosity of 2.8×10 -2 Pa.s, particles appeared at the channel corners even at 1.5 ml/h due to the low Re (Re = 0.3).…”

Section: Resultsmentioning

confidence: 99%

Size-Based Separation of Particles and Cells Utilizing Viscoelastic Effects in Straight Microchannels

et al. 2015

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Viscoelasticity-induced particle migration has recently received increasing attention due to its ability to obtain high-quality focusing over a wide range of flow rates. However, its application is limited to low throughput regime since the particles can defocus as flow rate increases. Using an engineered carrier medium with constant and low viscosity and strong elasticity, the sample flow rates are improved to be one order of magnitude higher than those in existing studies. Utilizing differential focusing of particles of different sizes, here we present sheathless particle/cell separation in simple straight microchannels that possess excellent parallelizability for further throughput enhancement. The present method can be implemented over a wide range of particle/cell sizes and flow rates. We successfully separate small particles from larger particles, MCF-7 cells from red blood cells (RBCs), and Escherichia coli (E. coli) bacteria from RBCs in different straight microchannels. The proposed method could broaden the applications of viscoelastic microfluidic devices to particle/cell separation due to the enhanced sample throughput and simple channel design.Continuous manipulation and separation of particles and cells is important for a wide range of applications in biology, 1,2 medicine, 2,3 and industry. [4][5][6] Microfluidic systems have been proven to be promising tools for particle/cell manipulation with higher sensitivity and accuracy than their macroscale counterparts. The last decade has seen extensive development of microfluidic approaches for particle/cell manipulation that resort to immunocapture, 7 externally applied physical fields, [8][9][10][11][12][13][14][15][16][17][18] microfiltration, 19,20 gravitational sedimentation, 21 or deterministic lateral migration. 22,23 More recently, cross-streamline migration induced by the hydrodynamic effects of carrier media, such as inertia 24,25 and viscoelasticity, 26,27 has shown its promise for effective particle/cell manipulation without need of labeling and external force fields. Particles and cells can be separated based on the size-dependent nature of hydrodynamic forces. Briefly, the inertial lift scales as F a ∝ , where a is the particle diameter. There are several cell types of biological and clinical interest with separable size ranges: epithelial tumor cells (15-25 µm in diameter), blood cells (erythrocytes are 6-8 µm biconcave disks and peripheral blood lymphocytes are 7-10 µm in diameter), and bacteria (1-3 µm). Inertial migration in Newtonian fluids has been intensively studied and implemented in high-throughput label-free separation devices for cell separation. [28][29][30][31][32][33][34] Recently, particle migration induced by viscoelasticity has begun to attract increasing attention due to its simple focusing pattern and potential for achieving efficient focusing over a wide range of flow rates. 35,36 In a viscoelastic medium, elasticity coupled with non-negligible inertia will drive particles towards the channel centerline, whic...

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“…Even in the case of synthetic polymers, the elasticity number El (Wi/Re l relax m/2rR 2 ) can be further enhanced if polymers are dissolved into highly viscous media. However, high pressure is required to drive high flow rates when such viscous media are used as working fluids 20 , which is an obvious drawback for portable microfluidic applications. Our present study demonstrates that in dilute DNA solutions it is possible to achieve significantly high El value at low viscosities (B2 cP), which allows high flow rates at low pumping pressures.…”

Section: Resultsmentioning

confidence: 99%

“…The lateral particle migration under macroscopic flows has long been recognized 16 . Additionally, two-dimensional (2D) (midplane) particle focusing in a slit microchannel 18 and 3D focusing in a square microchannel 19 or a microtube 20 have recently been reported. The shear viscosity of a dilute l-DNA solution (0.0005 (w/v)% in the present work) is nearly constant irrespective of shear rate (Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the dilute DNA solution is considered to be a Boger fluid, which can be described with Oldroyd-B model 21 . By using a modelling procedure based on previous works 18,20,22 (see Methods for the modelling and direct comparative studies between the theoretical prediction and experimental data ( Supplementary Fig. S2)), the lateral particle migration speed (V) normalized with axial average velocity /uS, can be denoted as:…”

Section: Resultsmentioning

confidence: 99%

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DNA-based highly tunable particle focuser

et al. 2013

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DNA is distinguished by both long length and structural rigidity. Classical polymer theories predict that DNA enhances the non-Newtonian elastic properties of its dilute solution more significantly than common synthetic flexible polymers because of its larger size and longer relaxation time. Here we exploit this property to report that under Poiseuille microflow, rigid spherical particles laterally migrate and form a tightly focused stream in an extremely dilute DNA solution (0.0005 (w/v)%). By the use of the DNA solution, we achieve highly efficient focusing (499.5%) over an unprecedented wide range of flow rates (ratio of maximum to minimum flow rates B400). This highly tunable particle-focusing technique can be used in the design of cost-effective portable flow cytometers, high-throughput cell analysis and also for cell sorting by size. We demonstrate that DNA is an efficient elasticity enhancer, which originates from its unique structural properties.

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Single line particle focusing induced by viscoelasticity of the suspending liquid: theory, experiments and simulations to design a micropipe flow-focuser

Cited by 186 publications

References 23 publications

Dynamics of particle migration in channel flow of viscoelastic fluids

Dynamics of particle migration in channel flow of viscoelastic fluids

Size-Based Separation of Particles and Cells Utilizing Viscoelastic Effects in Straight Microchannels

DNA-based highly tunable particle focuser

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