Batch-mode mixing on centrifugal microfluidic platforms

Grumann, M.; Geipel, Andreas; Riegger, L.; Zengerle, Roland; Ducrée, Jens

doi:10.1039/b418253g

Cited by 247 publications

(217 citation statements)

References 23 publications

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“…8, which are published as supporting information on the PNAS web site). Finally, we note that analogous flow phenomena can arise in conduits subjected to spanwise rotation [e.g., in microchannels constructed on a rotating platform (42,43)] where transverse flows are generated by Coriolis effects and the Rossby number plays a comparable role to the Dean number (44, 45). ASM.…”

Section: A Ratio Of Corresponding Timescales Is Thenmentioning

confidence: 99%

Multivortex micromixing

Sudarsan

Ugaz

2006

Proc. Natl. Acad. Sci. U.S.A.

294

221

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The ability to mix liquids in microchannel networks is fundamentally important in the design of nearly every miniaturized chemical and biochemical analysis system. Here, we show that enhanced micromixing can be achieved in topologically simple and easily fabricated planar 2D microchannels by simply introducing curvature and changes in width in a prescribed manner. This goal is accomplished by harnessing a synergistic combination of (i) Dean vortices that arise in the vertical plane of curved channels as a consequence of an interplay between inertial, centrifugal, and viscous effects, and (ii) expansion vortices that arise in the horizontal plane due to an abrupt increase in a conduit's cross-sectional area. We characterize these effects by using confocal microscopy of aqueous fluorescent dye streams and by observing binding interactions between an intercalating dye and double-stranded DNA. These mixing approaches are versatile and scalable and can be straightforwardly integrated as generic components in a variety of lab-on-a-chip systems.Dean flow ͉ expansion vortex ͉ microfluidics ͉ lab on a chip A lthough microf luidic mixing is a key process in a host of miniaturized analysis systems (1-7), it continues to pose challenges owing to constraints associated with operating in an unfavorable laminar f low regime dominated by molecular diffusion and characterized by a combination of low Reynolds numbers (Re ϭ Vd͞v Ͻ Ͻ 100, where V is the f low velocity, d is a length scale associated with the channel diameter, and v is the f luid kinematic viscosity) and high Péclet numbers (Pe ϭ Vd͞D Ͼ 100, where D is the molecular diffusivity). The relatively large discrepancy between convective and diffusive timescales implies that in a straight smooth-walled microchannel, the downstream distances over which liquids must travel to become fully intermixed (⌬y m ϳ Vd 2 ͞D ϭ Pe ϫ d) can be on the order of several centimeters. These mixing lengths are generally prohibitively long and often negate many of the benefits of miniaturization.A wide variety of micromixing approaches have been explored (8, 9), most of which can be broadly classified as either ''active'' (involving input of external energy) or ''passive'' (harnessing the inherent hydrodynamic structure of specific flow fields to mix fluids in the absence of external forces). Passive designs are often desirable in applications involving sensitive species (e.g., biological samples) because they do not impose strong mechanical, electrical, or thermal agitation. Examples of passive micromixing approaches that have been widely investigated include the following: (i) ''split-and-recombine'' strategies where the streams to be mixed are divided or split into multiple channels and redirected along trajectories that allow them to be subsequently reassembled as alternating lamellae yielding exponential reductions in interspecies diffusion length and time scales (4, 10-12); and (ii) ''chaotic'' strategies where transverse flows are passively generated that continuously expand interfacial...

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Section: A Ratio Of Corresponding Timescales Is Thenmentioning

confidence: 99%

Multivortex micromixing

Sudarsan

Ugaz

2006

Proc. Natl. Acad. Sci. U.S.A.

294

221

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“…The other group is designed for mixing two or more fluids [5,7,9,10,13]. The main idea in this kind of micromixer is to use momentum transfer between magnetic beads and fluid flow to induce some disturbances in the flow field and as a result mixing occurs.…”

Section: Introductionmentioning

confidence: 99%

“…Their design was based on the dynamic motion of a selfassembled structure of ferrimagnetic beads that are retained within a microfluidic flow using a local alternating magnetic field. Grumann et al [13] introduced a novel magnetic bead micromixer in which magnetic beads are filled in a disk-based mixing chamber. The disk is exposed to a magnetic field created by a set of permanent magnets resting in the lab-frame.…”

Section: Introductionmentioning

confidence: 99%

Effects of Magnetic Particles Entrance Arrangements on Mixing Efficiency of a Magnetic Bead Micromixer

2014

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Abstract:In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance, particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and compared. The results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.

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“…This can be further enhanced by placing obstacles in the channel or introducing curvatures and abrupt changes in cross-sectional area of the channels to promote chaotic advection or vortex mixing. Other mixers, especially suited for centrifugal microfluidics explore the Coriolis force present in rotating systems to induce secondary flows and promote mixing [3] or use periodically changing angular accelerations to perform batch mixing [4].…”

Section: Introductionmentioning

confidence: 99%

Droplet Mixer based on Siphon-Induced Flow Discretization and Phase Shifting

Burger

Reis

Fonseca

et al. 2009

2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems

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We present a novel mixing principle for centrifugal microfluidic platforms. Siphon structures are designed to disrupt continuous flows in a controlled manner into a sequence of discrete droplets, displaying individual volumes as low as 60 nL. When discrete volumes of different liquids are alternately issued into a common reservoir, a striation pattern of alternating liquid layers is obtained.In this manner diffusion distances are drastically decreased and a fast and homogeneous mixing is achieved. Efficient mixing is demonstrated for a range of liquid combinations of varying fluid properties such as aqueous inks or saline solutions and human plasma. Volumes of 5 ptL have been mixed in less than 20 s to a high mixing quality. One-step dilutions of plasma in a standard phosphate buffer solution up to 1:5 are also demonstrated.

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Batch-mode mixing on centrifugal microfluidic platforms

Cited by 247 publications

References 23 publications

Multivortex micromixing

Multivortex micromixing

Effects of Magnetic Particles Entrance Arrangements on Mixing Efficiency of a Magnetic Bead Micromixer

Droplet Mixer based on Siphon-Induced Flow Discretization and Phase Shifting

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