Efficient electroosmotic mixing in a narrow-fluidic channel: the role of a patterned soft layer

Gaikwad, Harshad Sanjay; Kumar, Gaurav; Mondal, Pranab Kumar

doi:10.1039/d0sm00890g

Cited by 33 publications

(27 citation statements)

References 39 publications

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“…The effect of convection on the ion distribution becomes negligible as the order of ionic Péclet number is small (Pe i ∼ O[10 −2 − 10 −4 ]) [36]. Apart from that for the present case, the order of EDL field is much larger than the order of applied electric field (O(ζ * a /λ D ) O( V /L total )).…”

Section: Governing Transport Equationsmentioning

confidence: 52%

“…Apart from that for the present case, the order of EDL field is much larger than the order of applied electric field (O(ζ * a /λ D ) O( V /L total )). Therefore, the weak-field approximation [36] is valid for the present case. Here, ζ * a is the amplitude of the nonuniform zeta potential.…”

Section: Governing Transport Equationsmentioning

confidence: 83%

“…The steady-state EDL-potential distribution for the wavy micromixer is given by the Poisson-Nernst-Planck model [36]. The corresponding dimensionless equations can be written as:…”

Section: Governing Transport Equationsmentioning

confidence: 99%

“…Since a relatively higher flow rate is essential for the rapid detection of biosamples, it becomes a difficult task indeed to retain the samples up to the desired time, ensuring proper mixing in the onchip platform. As such, the constraint of the minimal sample volume requirement alongside the demand for fast detection of samples for effective diagnosis has compelled researchers to adopt several means of electroosmotic mixing in lab-on-a-chip (LOC)-based microfluidic platform in recent times [31][32][33][34][35][36]. The unique aspect of EOF, like the formation of vortices due to the pattern charged surfaces, allows enhancement of the mixing quality.…”

Section: Introductionmentioning

confidence: 99%

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Numerical study of the vortex‐induced electroosmotic mixing of non‐Newtonian biofluids in a nonuniformly charged wavy microchannel: Effect of finite ion size

2021

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We propose a micromixer for obtaining better efficiency of vortex induced electroosmotic mixing of non-Newtonian bio-fluids at a relatively higher flow rate, which finds relevance in many biomedical and biological applications. To represent the rheology of non-Newtonian fluid, we consider the Carreau model in this study, while the applied electric field drives the constituent components in the micromixer. We show that the spatial variation of the applied field, triggered by the topological change of the bounding surfaces, upon interacting with the non-uniform surface potential gives rise to efficient mixing as realized by the formation of vortices in the proposed micromixer. Also, we show that the phase-lag between surface potential leads to the formation of asymmetric vortices. This behavior offers better mixing performance following the appearance of undulation on the flow pattern. Finally, we establish that the assumption of a point charge in the paradigm of electroosmotic mixing, which is not realistic as well, under-predicts the mixing efficiency at higher amplitude of the non-uniform zeta potential. The inferences of the present analysis may guide as a design tool for micromixer where rheological properties of the fluid and flow actuation parameters can be simultaneously tuned to obtain phenomenal enhancement in mixing efficiency.

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Section: Governing Transport Equationsmentioning

confidence: 52%

Section: Governing Transport Equationsmentioning

confidence: 83%

“…The steady-state EDL-potential distribution for the wavy micromixer is given by the Poisson-Nernst-Planck model [36]. The corresponding dimensionless equations can be written as:…”

Section: Governing Transport Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical study of the vortex‐induced electroosmotic mixing of non‐Newtonian biofluids in a nonuniformly charged wavy microchannel: Effect of finite ion size

2021

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“…Liquid metals (LM) combine naturally the low dynamic viscosity of liquids and the high electric conductivity of solid metals that usually serve as conducting probes for actuating electroosmosis and electrophoresis in micro/nanofluidic channels [1–4], which have made them broadly used in the field of miniaturized electronic and fluidic devices [5–9]. LM can be patterned conveniently and flexibly integrated into microfluidic systems as active pumps, conducting electrodes as well as dynamic valves [10].…”

Section: Introductionmentioning

confidence: 99%

Pumping of electrolyte with mobile liquid metal droplets driven by continuous electrowetting: A full‐scaled simulation study considering surface‐coupled electrocapillary two‐phase flow

Liu

Tao

et al. 2020

Electrophoresis

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With the excellent merits of both solid conductors and rheological fluids, liquid metal (LM) provides new opportunities to serve as flexible building blocks of miniaturized electronic and fluidic devices. The phenomenon of continuous electrowetting (CEW) has been long utilized for actuating LM contents in buffer medium, wherein an externally imposed voltage difference is responsible of manipulating the interfacial tension of deformable LM droplets. CEW effectively lowers the surface tension at the LM/electrolyte interface by driving bipolar counterions to the surface of conducting droplet. Since surface tension coefficient relies sensitively on the local voltage drop across the induced double layer, an electric‐analogy Marangoni effect occurs even under a rather weak electric field in the presence of a surface gradient of the interfacial tension. CEW of LM routinely induces unidirectional pumping of electrolyte in the direction of applied electric field, with LM droplet translating oppositely within the device channel. Although this subject has received great attention from the microfluidic society in the past decade, previous reports concerned either the individual delivery of the suspension medium or the transport of LM droplet. Starting from this point, we offer herein a fully coupled physical description of two‐phase flow dynamics occurring in CEW. The proposed simulation model successfully incorporates the synergy of the interfacial electrokinetic momentum transfer, surface tension on a curved surface, contact angle at the three‐phase contact line as well as the gravity force density. The spatial‐temporal motion of the contact interface is traced instantly with a moving mesh approach. By direct numerical simulation, the importance of the direct‐current bias, additional alternating‐current forcing, droplet size, initial ion adsorption in the process of CEW is addressed. Additionally, it is discovered that increasing the number of LM droplet is more cost‐effective than enhancing the volume of a single drop in terms of achieving an improvement of the resulted electrocapillary pump performance, while the translational speed of the discrete droplet carrier does not make an observable change in response to a variation in the drop number. These results prove invaluable in terms of an elaborate design of smart on‐chip electrokinetic frameworks embedding flexible LM contents in modern micro‐total‐analytical systems.

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Dielectric polarization‐mediated efficient solute mixing: Effect of the geometrical configuration of polarizing blocks

Pandey

Mondal

2023

Electrophoresis

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We propose a novel technique, consistent with the induced charge electrokinetic (ICEK) phenomenon, for the efficient mixing of solute species at a microfluidic scale. A nonuniform bipolar electric double layer develops in the presence of an external electric field over a polarizable object is better known as the ICEK phenomenon. This ICEK is one of the most favorable techniques preferred for enhanced solute mixing in on‐chip microfluidic platforms. In the purview of the ICEK phenomenon, instead of using perfectly conducting polarizable objects, for the first time in this study, we employ polarizable dielectric objects of different sizes and shapes for efficient mixing of solute species. We show that different types of vortices developed in the flow pathway adjacent to the polarizable dielectric blocks help in yielding efficient mixing in the proposed configuration. The novelty of our work is embellished in two different perspectives, that is, first, concentrating on the influences of the physical properties of the polarizable dielectric block on the underlying mixing, and, second, focusing on their sizes, shapes, and the arrangements in tuning the underlying mixing phenomena.

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Efficient electroosmotic mixing in a narrow-fluidic channel: the role of a patterned soft layer

Abstract: We propose a novel and efficient mixing technique in a soft narrow-fluidic channel under the influence of electrical forcing.

Cited by 33 publications

References 39 publications

Numerical study of the vortex‐induced electroosmotic mixing of non‐Newtonian biofluids in a nonuniformly charged wavy microchannel: Effect of finite ion size

Numerical study of the vortex‐induced electroosmotic mixing of non‐Newtonian biofluids in a nonuniformly charged wavy microchannel: Effect of finite ion size

Pumping of electrolyte with mobile liquid metal droplets driven by continuous electrowetting: A full‐scaled simulation study considering surface‐coupled electrocapillary two‐phase flow

Dielectric polarization‐mediated efficient solute mixing: Effect of the geometrical configuration of polarizing blocks

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