Electrowetting of water and aqueous solutions on poly(ethylene terephthalate) insulating films

Vallet, Maxime; Berge, B.; Vovelle, Louis

doi:10.1016/0032-3861(96)85360-2

Cited by 261 publications

(214 citation statements)

References 6 publications

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“…17,18 When dealing with electrowetting on an insulator coated solid electrode, the relationship between the contact angle and the applied voltage is usually studied by a sessile drop experiment (see Fig. S1 in the ESI{) and described by Young-Lippmann equation: 19,20 cos h{ cos h 0~1 2…”

Section: Principle and Fundamental Studies Sessile Drop Experimentsmentioning

confidence: 99%

Asymmetric electrowetting—moving droplets by a square wave

et al. 2007

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Here droplet oscillation and continuous pumping are demonstrated by asymmetric electrowetting on an open surface with embedded electrodes powered by a square wave electrical signal without control circuits. The polarity effect of electrowetting on an SU-8 and Teflon coated electrode is investigated, and it is found that the h-V (contact angle-applied voltage) curve is asymmetric along the V = 0 axis by sessile drop and coplanar electrode experiments. A systematic deviation of measured contact angles from the theoretical ones is observed when the electrode beneath the droplet is negatively biased. In the sessile drop experiment, up to a 10u increment of contact angle is measured on a negatively biased electrode. In addition, a coplanar electrode experiment is designed to examine the contact angles at the same applied potential but opposite polarities on two sides of one droplet at the same time. The design of the coplanar electrodes is then expanded to oscillate and transport droplets on square-wave-powered symmetric (square) and asymmetric (polygon) electrodes to demonstrate manipulation capability on an open surface. The frequency of oscillation and the speed of transportation are determined by the frequency of the applied square wave and the pitch of the electrodes. Droplets with different volumes are tested by square waves of varied frequencies and amplitudes. The 1.0 ml droplet is successfully transported on a device with a loop of 24 electrodes continuously at a speed up to 23.6 mm s 21 when a 9 Hz square wave is applied.

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Section: Principle and Fundamental Studies Sessile Drop Experimentsmentioning

confidence: 99%

Asymmetric electrowetting—moving droplets by a square wave

et al. 2007

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“…[1][2][3][4][5][6][7][8][9][10] In practice, electro-wetting-based actuation of aqueous solutions is limited by the onset of current flow through the substrate and the solution, which leads to chemical oxidation, the reduction of solutes, and to electrolysis ͑bubble formation͒. It has recently been demonstrated that fluid actuation can be achieved without electrolysis by coating the conductor or semiconductor substrate with a dielectric.…”

Section: Introductionmentioning

confidence: 99%

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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“…In particular, surface tension effects are critical in microfluidic devices [6][7][8][9]. It has been shown that it is possible to effectively modify surface tension in a variety of ways, by varying temperature [10], by modifying surface chemistry [11], by actively changing surface roughness [12], and by applying electric fields [13][14][15], and all of these techniques can be used to control fluid flow on the micro-scale. Figure 2 shows a liquid drop of water on top of a dielectric layer.…”

Section: Control Of Flows Driven By Electrically Actuated Surface Tenmentioning

confidence: 99%