Variational formulation on Joule heating in combined electroosmotic and pressure driven microflows

Sadeghi, Arman; Saidi, Mohammad Hassan; Waezi, Zakariya; Chakraborty, Suman

doi:10.1016/j.ijheatmasstransfer.2013.01.065

Cited by 20 publications

(5 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to this method, the solution

F_{n}

of Eq. also minimizes the following integral over the dimensionless cross‐sectional area

A^{*}

I = \int_{A^{*}}^{} false[{false(\frac{\partial F_{n}}{\partial y^{*}} false)}^{2} + {false(\frac{\partial F_{n}}{\partial z^{*}} false)}^{2} - β_{n}^{2} (\frac{β_{n}^{2}}{{P e}^{2}} + u^{*}) F_{n}^{2} - \frac{1}{2} (\frac{\partial^{2} F_{n}^{2}}{\partial {y^{*}}^{2}} + \frac{\partial^{2} F_{n}^{2}}{\partial {z^{*}}^{2}}) false] normald A^{*}

…”

Section: Problem Formulationmentioning

confidence: 99%

Analytical solutions for species transport in a T‐sensor at low peclet numbers

Sadeghi

2016

AIChE Journal

Self Cite

View full text Add to dashboard Cite

A 3D analytical solution is presented for the problem of mass transport in a T-sensor by taking the axial diffusion effects into account. The solution methodology is based on an eigenfunction expansion of the solute concentration and enjoys the variational calculus for the solution of the associated eigenvalue problem. The method is capable of handling a mixed electroosmotic and pressure-driven velocity profile and is executed assuming a rectangular channel crosssection although it can be easily extended to more complex geometries. Two simplified models, one based on a uniform velocity profile, valid for the channel half height to Debye length ratios of above 100, and the other based on a depthwise averaging of the species concentration to be used for cases in which the channel width to height ratio is above 5 are also presented. As a part of the latter, expressions are derived for the Taylor dispersion coefficient of the mixed flow in a slit microconduit. The most interesting finding of this study is that, when the diffusion mechanism significantly contributes to the axial movement of the species, the well-known heterogeneous mass transport evolves into a nearly uniform pattern in the depthwise direction and the mixing length noticeably increases.The predictions of the thin EDL solution are also presented to be compared with those of C50.

show abstract

“…According to this method, the solution

F_{n}

of Eq. also minimizes the following integral over the dimensionless cross‐sectional area

A^{*}

I = \int_{A^{*}}^{} false[{false(\frac{\partial F_{n}}{\partial y^{*}} false)}^{2} + {false(\frac{\partial F_{n}}{\partial z^{*}} false)}^{2} - β_{n}^{2} (\frac{β_{n}^{2}}{{P e}^{2}} + u^{*}) F_{n}^{2} - \frac{1}{2} (\frac{\partial^{2} F_{n}^{2}}{\partial {y^{*}}^{2}} + \frac{\partial^{2} F_{n}^{2}}{\partial {z^{*}}^{2}}) false] normald A^{*}

…”

Section: Problem Formulationmentioning

confidence: 99%

Analytical solutions for species transport in a T‐sensor at low peclet numbers

Sadeghi

2016

AIChE Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Electrokinetic mechanisms often involve Joule heating, which is generated due to flow of electric current through the electrolyte. [33][34][35][36] Joule heating causes temperature gradient into the medium and affects the functionality of electrokinetic mechanisms and associated processes including biomedical, biochemical reactions. [37][38][39][40] Beyond a threshold temperature, properties of biological and biochemical samples are changed, and detrimental effects of Joule heating are observed.…”

Section: Introductionmentioning

confidence: 99%

Joule heating-induced particle manipulation on a microfluidic chip

et al. 2019

Self Cite

View full text Add to dashboard Cite

We develop an electrokinetic technique that continuously manipulates colloidal particles to concentrate into patterned particulate groups in an energy efficient way, by exclusive harnessing of the intrinsic Joule heating effects. Our technique exploits the alternating current electrothermal flow phenomenon which is generated due to the interaction between non-uniform electric and thermal fields. Highly non-uniform electric field generates sharp temperature gradients by generating spatially-varying Joule heat that varies along radial direction from a concentrated point hotspot. Sharp temperature gradients induce local variation in electric properties which, in turn, generate strong electrothermal vortex. The imposed fluid flow brings the colloidal particles at the centre of the hotspot and enables particle aggregation. Further, manoeuvering structures of the Joule heating spots, different patterns of particle clustering may be formed in a low power budget, thus, opening up a new realm of on-chip particle manipulation process without necessitating highly focused laser beam which is much complicated and demands higher power budget. This technique can find its use in Lab-on-a-chip devices to manipulate particle groups, including biological cells.

show abstract

“…Moreover, the high voltage in a microfluidic device causes detrimental effects to the chip including degradation of electrode, bubble formation, high Joule heating, etc. . Hence, this method cannot be integrated in a microfluidic chip executing multiple operations on the same platform.…”

Section: Introductionmentioning

confidence: 99%

Strong rotating flow in stationary droplets in low power budget using wire electrode configuration

2019

Self Cite

View full text Add to dashboard Cite

We explore a simple strategy of generating strong rotating flow in a stationary surface‐droplet, using an intricate interplay of local electrical and thermal fields. Wire electrodes are employed to generate on‐spot heating without necessitating any elaborate micro‐fabrication, which causes strong local gradients in electrical properties to induce mobile charges into the droplet. Applying a low voltage (∼10 V), strong rotational velocity of the order of mm/s can be achieved in the system, within the standard operating ranges of operating and geometrical parameters. Further, altering the diameter of the electrode, vortices can be tuned locally or globally in low power budget, without incurring any droplet oscillations. These results may turn out to be of immense consequence in enhancing micromixing in a plethora of droplet based applications ranging from thermal management to medical diagnostics to be potentially employed in resource‐limited settings.

show abstract

Variational formulation on Joule heating in combined electroosmotic and pressure driven microflows

Cited by 20 publications

References 39 publications

Analytical solutions for species transport in a T‐sensor at low peclet numbers

Analytical solutions for species transport in a T‐sensor at low peclet numbers

Joule heating-induced particle manipulation on a microfluidic chip

Strong rotating flow in stationary droplets in low power budget using wire electrode configuration

Contact Info

Product

Resources

About