Three Dimensional, Sheathless, and High‐Throughput Microparticle Inertial Focusing Through Geometry‐Induced Secondary Flows

Chung, Aram J.; Gossett, Daniel R.; Carlo, Dino Di

doi:10.1002/smll.201202413

Cited by 170 publications

(196 citation statements)

References 37 publications

(56 reference statements)

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“…The third focusing pattern can meet the demands where both particles focusing and trapping are needed at the same time. The proposed focusing method has following advantages: (i) sheathless, no sheath flow is used to eliminate the risk of dilution and contamination; (ii) high throughput, the flow rate can be as high as 700 µl min -1 in a single channel; (iii) good focusing performance (especially for large particles), a single-particle focusing can be achieved for 9.9 µm particles, which reaches the performance of most reported hydrodynamic microfluidic chip [11,35,44,48,54]; (iv) flexible focusing ability, three different focusing patterns can satisfy various demands, with their working condition adjustable by the geometry of cavity.…”

Section: Resultsmentioning

confidence: 94%

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Zhang

et al. 2013

J. Micromech. Microeng.

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G. (2013). Inertial focusing in a straight channel with asymmetrical expansion-contraction cavity arrays using two secondary flows. Journal of Micromechanics and Microengineering, 23 (8), 1-13. Inertial focusing in a straight channel with asymmetrical expansioncontraction cavity arrays using two secondary flows AbstractThe focusing of particles has a variety of applications in industry and biomedicine, including wastewater purification, fermentation filtration, and pathogen detection in flow cytometry, etc. In this paper a novel inertial microfluidic device using two secondary flows to focus particles is presented. The geometry of the proposed microfluidic channel is a simple straight channel with asymmetrically patterned triangular expansion-contraction cavity arrays. Three different focusing patterns were observed under different flow conditions: (1) a single focusing streak on the cavity side; (2) double focusing streaks on both sides; (3) half of the particles were focused on the opposite side of the cavity, while the other particles were trapped by a horizontal vortex in the cavity. The focusing performance was studied comprehensively up to flow rates of 700 μl min−1. The focusing mechanism was investigated by analysing the balance of forces between the inertial lift forces and secondary flow drag in the cross section. The influence of particle size and cavity geometry on the focusing performance was also studied. The experimental results showed that more precise focusing could be obtained with large particles, some of which even showed a single-particle focusing streak in the horizontal plane. Meanwhile, the focusing patterns and their working conditions could be adjusted by the geometry of the cavity. This novel inertial microfluidic device could offer a continuous, sheathless, and high-throughput performance, which can be potentially applied to high-speed flow cytometry or the extraction of blood cells. (1) single focusing streak on cavity side; (2) double focusing streaks on both sides; (3) half of particles focused on the opposite side of cavity, and other particles trapped by horizontal vortex in cavity. The focusing performance was studied comprehensively up to the flow rates of 700 µl min -1 . The focusing mechanism was investigated by analyzing force balance between inertial lift forces and secondary flow drag in the cross section.The influence of particle size and cavity geometry on the focusing performance was also studied. Experimental results showed that a more pronounced focusing performance can be obtained with large particles, which even showed a single-particle focusing streak in horizontal plane. Meanwhile, focusing patterns and their working conditions were adjustable by the geometry of cavity. The novel inertial microfluidic device was capable of offering a continuous, sheathless, and high-throughput performance, which can be potentially applied to highspeed flow cytometry or extraction of blood cells.

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Section: Resultsmentioning

confidence: 94%

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Zhang

et al. 2013

J. Micromech. Microeng.

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“…This type of high quality focusing is important for both high precision positional focusing and due to the correlation between this single point focusing and consistent longitudinal ordering between particles 23,36 . It is also of note that single point particle focusing is possible in simple curved channels not requiring the more complicated structures required for the other known techniques for sheathless alignment of particles 26,37,38 . For the current data set these single point focusing conditions also represent the minimum streak width over the entire parameter space for each particle size Not all of the smallest particles are forced to a single point in this device, however, the existence of the streak near the inner wall indicates that the equilibrium position is present but perhaps the channel was not long enough for all particles to traverse to this position.…”

Section: Resultsmentioning

confidence: 99%

Particle Focusing in Curved Microfluidic Channels

Martel

Toner

2013

Sci Rep

173

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The decoupled effects of Reynolds and Dean numbers are examined in inertial focusing flows. In doing so, a complex set of inertial focusing behavioral regimes is discovered within curved microfluidic channels over a range of channel Reynolds numbers, curvature ratios and particle confinement ratios. These regimes are characterized by particle migration either towards or away from the center of curvature as the channel Reynolds number is increased. The transition between these two regimes is shown to be a set of conditions where single-point equilibrium position focusing of particles of different sizes is achieved. A mechanism describing the observed motion of particles in such flows is hypothesized incorporating the redistribution of the main flow velocities caused by Dean flow and its effect on the balance forces on suspended particles.I nertial focusing is an area of significant interest in the realm of microfluidics because it combines high throughput capability with precision particle positioning and offers theoretical intrigue due to the seemingly endless surprises that accompany experimental results. Inertial focusing occurs under certain conditions as particles flowing through a microchannel migrate across streamlines to equilibrium positions within the flow. This migration is due to inertial effects of the fluid motion around the particle and the interaction of this flow field with the walls of the channel 1-5 . Equilibrium positions arise from a balance between two distinct effects; a shear gradient lift force directed towards the walls of the channel and an opposing wall effect 6,7 . These forces allow for the precise alignment of particles in a flow at throughputs orders of magnitudes higher than in previous microfluidic technologies. The high throughput nature of inertial focusing has enabled a range of microfluidic technologies for biomedical applications from separation technologies [8][9][10][11][12] , to automated sample preparations 13,14 , to novel cell analysis techniques such as cell deformability cytometry 15 and the isolation of circulating tumor cells from blood 16,17 .It is generally accepted that inertial focusing in straight channels is dependent on two main parameters: Reynolds number, defined as Re C 5 rU Max D h /m, where r is the fluid density, m is the fluid viscosity, U Max > 3/2U Avg is the maximum velocity of the fluid and D h is the hydraulic diameter of the channel defined as D h 5 2hw/(h 1 w) where h and w are the height and width of the channel cross section respectively, and the particle confinement ratio, l 5 a/D h , where a, is the particle size. Prior research has determined a minimum threshold for inertial focusing to occur such that l . 0.07 and Re C l 2 , also known as the particle Reynolds number, Re P , is $1 18 . The equilibrium positions can be further controlled using curved channels, where a secondary flow called Dean flow is established at finite Re C . The strength of this secondary flow is characterized by the inertia of the fluid and the curvature of the cha...

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“…Therefore, a pixel has a high s.d. value (white-colored regions in STD plots) if particles frequently pass through the pixel and this qualitatively depicts the distribution of particle trajectories 51,52 . The specific conditions of imaging procedure for each image were denoted in Supplementary Method.…”

Section: Polymer Contribution To the Viscosity Of A Polymer Solution mentioning

confidence: 93%

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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Three Dimensional, Sheathless, and High‐Throughput Microparticle Inertial Focusing Through Geometry‐Induced Secondary Flows

Cited by 170 publications

References 37 publications

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Inertial focusing in a straight channel with asymmetrical expansion–contraction cavity arrays using two secondary flows

Particle Focusing in Curved Microfluidic Channels

DNA-based highly tunable particle focuser

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