High Throughput‐Per‐Footprint Inertial Focusing

Çiftlik, Ata Tuna; Ettori, Maxime; Gijs, Martin A. M.

doi:10.1002/smll.201201770

Cited by 65 publications

(70 citation statements)

References 34 publications

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“…For example, these side streaks emerge at certain Re C values that scale with ,l 0.4 (,105 for l 5 0.066, ,140 for l 5 0.149 and ,180 for l 5 0.225). The existence of these side streaks also concurs with the decrease in positive lift coefficient found at increasing Re C [33][34][35] . The formation of these side streaks also indicates the limited distance over which the lateral wall effect forces are dominant.…”

Section: Resultssupporting

confidence: 79%

Particle Focusing in Curved Microfluidic Channels

Martel

Toner

2013

Sci Rep

178

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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Section: Resultssupporting

confidence: 79%

Particle Focusing in Curved Microfluidic Channels

Martel

Toner

2013

Sci Rep

178

173

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“…5B). Experiments at much higher Reynolds numbers have shown that additional focusing positions appear in channel corners [28,29], but we find no evidence of alternate focusing positions over the range Re = 30 − 180.…”

Section: Dependence Of Focusing Forces On Particle Size and Reynolds contrasting

confidence: 81%

Direct measurement of particle inertial migration in rectangular microchannels

et al. 2016

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“…3 New applications have since emerged, with inertial focusing in particular, leading to new methods for high-throughput cytometry. [4][5][6][7][8][9][10] More recently, fluid sculpting via inertial flow has been demonstrated through so-called "pillar programming." 11,12 See Fig.…”

Section: Introductionmentioning

confidence: 99%

Optimization of micropillar sequences for fluid flow sculpting

Stoecklein

Kim

et al. 2016

Physics of Fluids

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Inertial fluid flow deformation around pillars in a microchannel is a new method for controlling fluid flow. Sequences of pillars have been shown to produce a rich phase space with a wide variety of flow transformations. Previous work has successfully demonstrated manual design of pillar sequences to achieve desired transformations of the flow cross section, with experimental validation. However, such a method is not ideal for seeking out complex sculpted shapes as the search space quickly becomes too large for efficient manual discovery. We explore fast, automated optimization methods to solve this problem. We formulate the inertial flow physics in microchannels with different micropillar configurations as a set of state transition matrix operations. These state transition matrices are constructed from experimentally validated streamtraces for a fixed channel length per pillar. This facilitates modeling the effect of a sequence of micropillars as nested matrix-matrix products, which have very efficient numerical implementations. With this new forward model, arbitrary micropillar sequences can be rapidly simulated with various inlet configurations, allowing optimization routines quick access to a large search space. We integrate this framework with the genetic algorithm and showcase its applicability by designing micropillar sequences for various useful transformations. We computationally discover micropillar sequences for complex transformations that are substantially shorter than manually designed sequences. We also determine sequences for novel transformations that were difficult to manually design. Finally, we experimentally validate these computational designs by fabricating devices and comparing predictions with the results from confocal microscopy. C 2016 AIP Publishing LLC. [http://dx

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High Throughput‐Per‐Footprint Inertial Focusing

Cited by 65 publications

References 34 publications

Particle Focusing in Curved Microfluidic Channels

Particle Focusing in Curved Microfluidic Channels

Direct measurement of particle inertial migration in rectangular microchannels

Optimization of micropillar sequences for fluid flow sculpting

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