Droplet mixer based on electrowetting

Aghdaei, Sara; Green, Nicolas G.; Jones, Thomas B.; Morgan, Hywel

doi:10.1088/1742-6596/142/1/012071

Cited by 5 publications

(2 citation statements)

References 7 publications

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“…In the literature, various ideas for enhanced mixing have been explored; see the review by Suh et al [27]. Mixing in shaken sessile drops by EWOD [2,[28][29][30][31][32][33] is enhanced due to a "Stokes-drift"-like mechanism by the capillary waves on the liquid-air interface [31]. However, these methods are not suitable for sandwiched drops due to the reduced liquid-air interface.…”

Section: Discussionmentioning

confidence: 99%

Electrowetting-driven oscillating drops sandwiched between two substrates

et al. 2013

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Drops sandwiched between two substrates are often found in lab-on-chip devices based on digital microfluidics. We excite azimuthal oscillations of such drops by periodically modulating the contact line via ac electrowetting. By tuning the frequency of the applied voltage, several shape modes can be selected one by one. The frequency of the oscillations is half the frequency of the contact angle modulation by electrowetting, indicating a parametric excitation. The drop response to sinusoidal driving deviates substantially from sinusoidal behavior in a "stop and go" fashion. Although our simple theoretical model describes the observed behavior qualitatively, the resonances appear at lower frequencies than expected. Moreover, the oscillations produce a nonperiodic fluid transport within the drop with a typical velocity of 1 mm/s. In digital microfluidic devices, where the typical drop size is less than 1 mm, this flow can result in very fast mixing on the spot.

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Section: Discussionmentioning

confidence: 99%

Electrowetting-driven oscillating drops sandwiched between two substrates

et al. 2013

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“…24 In comparison, droplet coalescence on an EWOD device based on a SU-8 substrate requires y900 ms for homogenization. 25…”

Section: Coalescence Analysismentioning

confidence: 99%

Fast, active droplet interaction: coalescence and reactive mixing controlled by electrowetting on a superhydrophobic surface

et al. 2013

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A novel electrowetting-on-dielectrics (EWOD) device in open planar geometry allows probing of droplet mixing on a superhydrophobic substrate under quasi contact-free conditions. We demonstrate a droplet-based microreactor with integrated convective-flow mixing for the reactive-mixing of CaCl(2)/Na(2)CO(3) solutions. The device provides unique conditions for scattering, spectroscopy and imaging probes requiring an unobstructed droplet-access.

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Colloidal droplet desiccation on a electrowetting-on-dielectric (EWOD) platform

Ghosh,

Dhara,

Bakshi

et al. 2024

Biomicrofluidics

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The physics of the effects of electric field on the desiccation of colloidal droplets, comprising of dispersed negatively charged nanoparticles [2 μl, 1(w/w. %)], are studied in a standard electrowetting-on-a-dielectric configuration. The extent of contact line pinning during evaporation is found to be a function of the magnitude of the applied voltage and quantified in terms of the dimensionless electrowetting number (η). The pinned contact line led to higher particle compaction as evidenced by the characterization of dried colloidal film thicknesses. Crack formation and their dynamics have been analyzed in detail to elicit the interplay of forces near the contact line region and on the compaction front. These aspects of crack formation are elucidated in the light of magnitude and polarity of the applied electric field. It is found to influence the crack front initiation velocity, the geometry, the number of cracks, and an attempt is made to explain the same via first principle-based approaches. Therefore, this study indicates the possibility of using electrowetting as a technique to fine-tune the crack formation behavior in thin colloidal films.

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Droplet mixer based on electrowetting

Cited by 5 publications

References 7 publications

Electrowetting-driven oscillating drops sandwiched between two substrates

Electrowetting-driven oscillating drops sandwiched between two substrates

Fast, active droplet interaction: coalescence and reactive mixing controlled by electrowetting on a superhydrophobic surface

Colloidal droplet desiccation on a electrowetting-on-dielectric (EWOD) platform

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