Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Sridharan, Sriram; Zhu, Junjie; Hu, Guoqing; Xuan, Xiangchun

doi:10.1002/elps.201100011

Cited by 96 publications

(135 citation statements)

References 54 publications

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“…Such a flow in the form of fluid circulation under appropriate conditions was later experimentally verified by the authors of this paper in a microchannel with a widthwise constriction (i.e. a 2D constriction) [28]. Hawkins and Kirby's model also predicted that the electrothermal flow enhances the DEP particle deflection and trapping in almost all cases [27].…”

Section: Introductionsupporting

confidence: 54%

“…Electrothermal flow can be induced by the interaction of the electric field and JH-induced fluid conductivity and permittivity gradients in the channel constriction region [27]. This flow is superimposed on the electrokinetic flow and not streamwise, and may even involve fluid circulations as demonstrated in [28]. Therefore, JH is expected to have a direct impact on the above-analyzed electrokinetic focusing and trapping of particles in constriction microchannels. )…”

Section: Mechanism Of Electrokinetic Particle Focusing and Trappingmentioning

confidence: 99%

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Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels

Zhu

Sridharan

et al. 2012

J. Micromech. Microeng.

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Joule heating (JH) is a ubiquitous phenomenon in electrokinetic microfluidic devices. Its effects on fluid and ionic species transport in capillary and microchip electrophoresis have been well studied. However, JH effects on the electrokinetic motion of microparticles in microchannels have been nearly unexplored in the literature. This paper presents an experimental investigation of JH effects on electrokinetic particle transport and manipulation in constriction microchannels under both pure dc and dc-biased ac electric fields. It is found that the JH effects reduce the dielectrophoretic focusing and trapping of particles, especially significant when dc-biased ac electric fields are used. These results are expected to provide a useful guidance for future designs of electrokinetic particle handling microdevices that will avoid JH effects or take advantage of them.

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Section: Introductionsupporting

confidence: 54%

Section: Mechanism Of Electrokinetic Particle Focusing and Trappingmentioning

confidence: 99%

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels

Zhu

Sridharan

et al. 2012

J. Micromech. Microeng.

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“…In these iDEP devices, the voltages are applied across a significant portion of the microchannel increasing the complexities due to heating effects. 18,19 In the current study, electrodes are located within the vicinity of the insulating microposts to minimize heat build-up within the channel. Reduced electrode spacing minimizes the conductive path travelled by the current ultimately reducing heat generated within the microchannel.…”

Section: Introductionmentioning

confidence: 99%

Three dimensional passivated-electrode insulator-based dielectrophoresis

et al. 2015

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In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D pDEP) is presented. This technology combines the benefits of electrodebased DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D pDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 lm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D pDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 ll/h and 70% at flow rates as high as 750 ll/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape. V C 2015 AIP Publishing LLC.

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“…19,20 This so-called electrothermal flow arises from the action of electric field on the inhomogeneous temperature-dependent fluid properties. 21,22 More recently, our group has reported an electrokinetic in-reservoir pre-concentration of particles and bacterial cells, 23 where Joule heating effects can be safely neglected due to the use of a low ionic concentration fluid. 24,25 We have attributed this phenomenon to the recirculating flow of induced charge electroosmosis (ICEO) at the channel entrance.…”

Section: Introductionmentioning

confidence: 99%

Induced charge effects on electrokinetic entry flow

et al. 2017

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Electrokinetic flow, due to a nearly plug-like velocity profile, is the preferred mode for transport of fluids (by electroosmosis) and species (by electrophoresis if charged) in microfluidic devices. Thus far there have been numerous studies on electrokinetic flow within a variety of microchannel structures. However, the fluid and species behaviors at the interface of the inlet reservoir (i.e., the well that supplies the fluid and species) and microchannel are still largely unexplored. This work presents a fundamental investigation of the induced charge effects on electrokinetic entry flow due to the polarization of dielectric corners at the inlet reservoir-microchannel junction. We use small tracing particles suspended in a low ionic concentration fluid to visualize the electrokinetic flow pattern in the absence of Joule heating effects. Particles are found to get trapped and concentrated inside a pair of counter-rotating fluid circulations near the corners of the channel entrance. We also develop a depth-averaged numerical model to understand the induced charge on the corner surfaces and simulate the resultant induced charge electroosmosis (ICEO) in the horizontal plane of the microchannel. The particle streaklines predicted from this model are compared with the experimental images of tracing particles, which shows a significantly better agreement than those from a regular two-dimensional model. This study indicates the strong influences of the top/bottom walls on ICEO in shallow microchannels, which have been neglected in previous two-dimensional models.

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Joule heating effects on electroosmotic flow in insulator‐based dielectrophoresis

Cited by 96 publications

References 54 publications

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels

Three dimensional passivated-electrode insulator-based dielectrophoresis

Induced charge effects on electrokinetic entry flow

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