Charge-Induced Modification of Contact Angle:  The Secondary Electrocapillary Effect

Digilov, Rafael M.

doi:10.1021/la991308a

Cited by 106 publications

(113 citation statements)

References 9 publications

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“…14͒ The limitation of this viewpoint has been recognized in some recent articles. 5,6,26 Essentially, if we have internal bulk forces as occur in the case of gravity ͑the simplest example͒ or because of internal electric fields such as the one shown in Fig. 4, then we must balance the bulk volume forces against the interfacial effects.…”

Section: Results Summarymentioning

confidence: 99%

“…1,7,10,13-25. In particular, the total energy minimization framework proposed by Digilov 26 is similar to our starting point. Howa͒ Author to whom correspondence should be addressed; electronic mail: benshap@eng.umd.edu; http://www.glue.umd.edu/ ϳ benshap/ ever, our method of analysis and physical interpretation is different; plus, we go on to numerically solve the surfaceenergy/electrostatic minimum energy conditions and we study the properties of the solutions.…”

Section: A Backgroundmentioning

confidence: 99%

“…In this sense, our analysis is similar in spirit to Digilov. 26 However, when necessary, we phrase and solve Maxwell's partial differential equations to find the electric fields, and thus the stored energies, inside the solid and liquid materials. Moreover, we have been able to derive a rigorous equation which takes any arbitrary energy term and analytically gives back the corresponding, sizedependent, force term in Young's equation.…”

Section: B Current Approachmentioning

confidence: 99%

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Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Shapiro

Moon

Garrell

et al. 2003

Journal of Applied Physics

204

183

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This article describes the equilibrium shape of a liquid drop under applied fields such as gravity and electrical fields, taking into account material properties such as dielectric constants, resistivities, and surface tension coefficients. The analysis is based on an energy minimization framework. A rigorous and exact link is provided between the energy function corresponding to any given physical phenomena, and the resulting shape and size dependent force term in Young's equation. In particular, the framework shows that a physical effect, such as capacitive energy storage in the liquid, will lead to 1/R ''line-tension''-type terms if and only if the energy of the effect is proportional to the radius of the liquid drop: EϰR. The effect of applied electric fields on shape change is analyzed. It is shown that a dielectric solid and a perfectly conducting liquid are all that is needed to exactly recover the Young-Lippmann equation. A dielectric liquid on a conducting solid gives rise to line tension terms. Finally, a slightly resistive liquid on top of a dielectric, highly resistive solid gives rise to contact angle saturation and accurately matches the experimental data that we observe in our electro-wetting-on-dielectric devices.

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Section: Results Summarymentioning

confidence: 99%

Section: A Backgroundmentioning

confidence: 99%

Section: B Current Approachmentioning

confidence: 99%

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Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Shapiro

Moon

Garrell

et al. 2003

Journal of Applied Physics

204

183

View full text Add to dashboard Cite

show abstract

“…The Young-Dupré equation was then used to compute the modified contact angle assuming no change in γ lv and γ sv . Digilov (2000) and Chou (2001) 438 DARHUBER TROIAN were concerned that the presence of a contact line at a charged surface might induce effects not accounted for by this simple substitution. Digilov concluded that the applied potential causes polarization of the interface and the three-phase contact line, which reduces both the interfacial tension and the line tension.…”

Section: Electrocapillary Phenomenamentioning

confidence: 99%

Principles of Microfluidic Actuation by Modulation of Surface Stresses

Darhuber

Troian

2005

Annu. Rev. Fluid Mech.

440

340

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Development and optimization of multifunctional devices for fluidic manipulation of films, drops, and bubbles require detailed understanding of interfacial phenomena and microhydrodynamic flows. Systems are distinguished by a large surface to volume ratio and flow at small Reynolds, capillary, and Bond numbers are strongly influenced by boundary effects and therefore amenable to control by a variety of surface treatments and surface forces. We review the principles underlying common techniques for actuation of droplets and films on homogeneous, chemically patterned, and topologically textured surfaces by modulation of normal or shear stresses.

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“…The mechanism for force generation in the direction horizontal to the interface has been clarified by other researchers. [19][20][21] Also, dependence of the performance on physical parameters has been analyzed by Ren and co-workers. 22 The driving voltage V needed to mobilize a liquid can be approximated as follows: 6 …”

Section: Principle Of Operationmentioning

confidence: 99%

Microfluidic transport based on direct electrowetting

Satoh

Loughran

Suzuki

2004

Journal of Applied Physics

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Access to the full text of the published version may require a subscription. An integrated microfluidic system was fabricated which functions by deliberately manipulating interfacial tension. A distinctive characteristic of our system is the use of an array of adjacent, elongated, working electrodes and protruding polydimethylsiloxane open-flow channels. Microfluidic transport was realized directly on the bare gold electrode surface in the absence of an additional dielectric layer. By changing the potential of the working electrode to a negative potential, a liquid column could be transported from one end of an elongated working electrode to the other end. Transport of the liquid column could be altered without any valves by switching on the adjacent electrode in a given direction. The flow velocity depended on the applied potential, i.e., the velocity could be altered by deliberate manipulation of the electrode potential. In addition, the flow velocity increased as the dimensions of the flow channel decreased. The applied voltage was less than 2 V, and the power consumption was in the order of tens of W. Rights

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Charge-Induced Modification of Contact Angle: The Secondary Electrocapillary Effect

Cited by 106 publications

References 9 publications

Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Equilibrium behavior of sessile drops under surface tension, applied external fields, and material variations

Principles of Microfluidic Actuation by Modulation of Surface Stresses

Microfluidic transport based on direct electrowetting

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