Acoustogravitational balance in climbing films

Horesh, Amihai; Khaikin, Daniel; Karnilaw, Mackenzie; Zigelman, Anna; Manor, Ofer

doi:10.1103/physrevfluids.4.022001

Cited by 5 publications

(7 citation statements)

References 22 publications

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“…Both the viscous penetration length in water, 2 / δ η ρω ≡ , and time scale, ω −1 , of a SAW may become comparable to the Debye length, σ, and relaxation time, σ 2 /D, of an EDL, where η, ρ, ω, and D denote the liquid viscosity, liquid density, SAW angular frequency, and ion thermal diffusion coefficient, respectively. For example, SAW frequencies of ω/2π = 10 7 − 10 9 Hzcommon in microfluidic applicationsgive δ ≈ 10 SAWs and EDLs may possess comparable time and length scales and may become entangled through electrokinetic effects.…”

Section: ■ Introductionmentioning

confidence: 99%

“…It was lately demonstrated that surface acoustic waves (SAWs) are capable of manipulating and pumping liquids in nanochannels, , supporting dynamic wetting, − atomizing liquids, and manipulating the attachment of drops to SAW-actuated surfaces . In addition, SAWs were found to actuate submicron-thick electrolyte solutions for the analysis and manipulation of biochemical and biological agents, push water through membranes that comprise graphene nanochannels for eliminating nanometer-sized pollutants, and power paper-based microfluidics. − The unifying property in the above applications is the presence of SAWs near electrolyte solutions of nanometer and submicron length scales.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the Electroacoustic Phenomenon in the Presence of Surface Acoustic Waves

Dubrovski

Manor

2021

Langmuir

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Recently, one has been observing abundant studies on the application of surface acoustic waves (SAWs) in solid substrates for manipulating liquids and particulates in micron-to-nanometer thick films and channels and in porous media. At these length scales, contributions of SAWs to the electrical double layer (EDL) of ions and of the latter to particulates and flow may become appreciable. However, the nature of the interplay between SAWs and EDLs is unknown. We demonstrate the contribution of a SAW to the near-equilibrium electrical and ion-concentration fields in an EDL near inert and piezoelectric substrates. In particular, we concentrate on the leakage of transient and steady components of electrical potential through the excited EDL. Far from the solid, the leakage may be interpreted by different models of the EDL to give information about the EDL characteristic relaxation time, ζ-potential, and the Stern layer therein. In addition, the analysis given here may explain observed SAW-induced electrochemical effects on piezoelectric substrates.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revisiting the Electroacoustic Phenomenon in the Presence of Surface Acoustic Waves

Dubrovski

Manor

2021

Langmuir

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“…The climb height of the oil over the drop is known to be the result of acoustic, capillary, and gravitational stresses in the therein. [44] Corresponding movies of the experiment are given in Supporting Information. To evaluate the contribution of the SAW to the coating process, we further give time lapse images of the interaction of the oil film and a water drop on our actuator, but in the absence of SAW (no power is applied to the actuator) in Fig 3 . The figure demonstrates that in the absence of SAW, the oil slowly and spontaneously spreads across the LN surface due to its low surface tension.…”

Section: Resultsmentioning

confidence: 99%

Active coating of a water drop by an oil film using a MHz-frequency surface acoustic wave

Reizman¹,

Horesh²,

Kondic³

et al. 2023

Preprint

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We employ a millimeter-scale piezoelectric acoustic actuator, which generates MHz-frequency surface acoustic waves (SAWs) in a solid substrate, to actively coat a drop of water by a macroscopic film of silicon oil as a paradigm for a small scale and low power coating system. We build upon previous studies on SAW induced dynamic wetting of a solid substrate, also known as the acoustowetting phenomena, to actively drive a model low surface-energy liquid -silicon oil -coat a model liquid object -a sessile drop of water. The oil film spreads along the path of the propagating SAW and comes in contact with the drop, which is placed in its path. The intensity of the SAW determines the rate and the extent to which a macroscopically thick film of oil will climb over the drop to partially or fully cover its surface. The dynamic wetting of the drop by the oil film is governed by a balance between acoustic, capillary, and gravitational contributions. Introducing a water drop as an object to be coated indicates the opportunity to coat liquid phase objects by employing SAWs and demonstrates that oil films which are actuated by SAWs may traverse curved objects and liquid surfaces.

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“…While this capillary pressure is still greater than what could realistically be generated from traditional acoustic streaming, it is still three orders of magnitude less than the ∼1 MPa capillary pressure of water in filling the nanoslit channel from the outside. Lithium niobate is hydrophilic with a contact angle [ 37 ] of about 25°, so channels formed of LN tend to easily fill.…”

Section: Resultsmentioning

confidence: 99%

Manipulation and Mixing of 200 Femtoliter Droplets in Nanofluidic Channels Using MHz‐Order Surface Acoustic Waves

2021

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Controllable manipulation and effective mixing of fluids and colloids at the nanoscale is made exceptionally difficult by the dominance of surface and viscous forces. The use of megahertz (MHz)-order vibration has dramatically expanded in microfluidics, enabling fluid manipulation, atomization, and microscale particle and cell separation. Even more powerful results are found at the nanoscale, with the key discovery of new regimes of acoustic wave interaction with 200 fL droplets of deionized water. It is shown that 40 MHz-order surface acoustic waves can manipulate such droplets within fully transparent, high-aspect ratio, 100 nm tall, 20-130 micron wide, 5-mm long nanoslit channels. By forming traps as locally widened regions along such a channel, individual fluid droplets may be propelled from one trap to the next, split between them, mixed, and merged. A simple theory is provided to describe the mechanisms of droplet transport and splitting.

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Acoustogravitational balance in climbing films

Cited by 5 publications

References 22 publications

Revisiting the Electroacoustic Phenomenon in the Presence of Surface Acoustic Waves

Revisiting the Electroacoustic Phenomenon in the Presence of Surface Acoustic Waves

Active coating of a water drop by an oil film using a MHz-frequency surface acoustic wave

Manipulation and Mixing of 200 Femtoliter Droplets in Nanofluidic Channels Using MHz‐Order Surface Acoustic Waves

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