Liquid-body resonance while contacting a rotating superhydrophobic surface

Chong, Matthew Lai Ho; Cheng, Ming; Katariya, Mayur; Muradoglu, Murat; Cheong, Brandon Huey Ping; Zahidi, Alifa Afiah Ahmad; Yu, Yong; Liew, Oi Wah; Ng, Tuck Wah

doi:10.1140/epje/i2015-15119-y

Cited by 5 publications

(5 citation statements)

References 37 publications

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“…The circumference of the hole then contributes more strongly to the liquid–solid interface area requirement despite it retaining a Cassie wetting state. It should also be noted that the manner in which sessile drops with high contact angles are being constrained on inclines makes them less stable, imbuing them with a propensity to resonate when periodic , or stochastic , perturbations are introduced. We have noticed a similar resonant motion with perturbations, which may be linked to the geometry and composition of the liquid body.…”

Section: Resultsmentioning

confidence: 99%

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Chung¹,

Huynh²,

Katariya³

et al. 2017

ACS Omega

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Drops with larger volumes placed over a superhydrophobic (SH) surface with a hole do not fall through unless they are evaporated to a size that is small enough. This feature offers the ability to preconcentrate samples for biochemical analysis. In this work, the influence of pinning on the behavior of drops placed on a 0.1 mm thick SH substrate with a 2 mm diameter hole as they evaporated was investigated. With 16 μL of water dispensed, the sessile drop component volume was initially higher than that of the overhanging drop component and maintained this until the later stages where almost identical shapes were attained and full evaporation was achieved without falling off the hole. With 15 μL of water dispensed, the volume of the sessile drop was initially higher than that of the overhanging drop component but the liquid body was able to squeeze through the hole after 180 s due to the contact line not having sufficient pinning strength when it encountered the edge of the hole. This resulted in the liquid body either falling through the hole or remaining pinned with an oval-like shape. When it did not fall-off, the liquid body had volume and contact angle characteristics for the sessile drop and overhanging drop components that were reversed. In the later stages, however, nearly identical shapes were again attained and full evaporation was achieved without falling off the hole. The effects of pinning, despite the substrate being SH, offer another path toward achieving practical outcomes with liquid bodies without the need for chemical surface functionalization. Similarities and differences could be seen in the behavior of a sessile drop on a SH plate that was inclined at 30° to the horizontal and evaporated.

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Section: Resultsmentioning

confidence: 99%

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Chung¹,

Huynh²,

Katariya³

et al. 2017

ACS Omega

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“…Because the liquid body is subject to this form of perturbation, the surface tension forces involved can drive it to respond dynamically. This is also possible because of compressed air being used here which generates a more stochastic driving impetus as opposed to gravity forces acting alone. , It is noteworthy that resonant behavior had previously been observed in the presence of stochastic perturbations − and has been found to occur notwithstanding the small restoring forces developed from SH surfaces. , Although some small extent of this was discerned, the relatively short time period leading to dislodgement does not furnish the means to confirm this.…”

Section: Resultsmentioning

confidence: 79%

“…18,23 It is noteworthy that resonant behavior had previously been observed in the presence of stochastic perturbations 31−33 and has been found to occur notwithstanding the small restoring forces developed from SH surfaces. 32,33 Although some small extent of this was discerned, the relatively short time period leading to dislodgement does not furnish the means to confirm this.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Simultaneous Multidrop Creation with Superhydrophobic Wells for Field Environmental Sensing of Nanoparticles

et al. 2018

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Facile creation of multiple drops at appropriate volumes on surfaces without the use of sophisticated instrumentation facilitates downstream evaporative preconcentration of liquid samples for analytical purposes. In this work, a superhydrophobic (SH) substrate comprising wells with a perforated mesh base was developed for simultaneous drop creation in a quick and convenient manner. In contrast to the method of pouring liquid directly over the SH wells, consistent liquid filling was readily achieved by a simple immersion approach. This method works well even for challenging situations where well diameters are smaller than 3.4 mm. Despite the poor liquid-retention properties of SH surfaces, inverting the wells did not result in liquid detachment under gravitational force, indicating strong pinning effects afforded by the well architecture. The perforated base of the well allowed the liquid to be completely removed from the well by compressed air. High-speed camera image processing was used to study the evolution of drop contact angle and displacement with time. It was found that the liquid body was able to undergo strong oscillations. Optical spectroscopy was used to confirm the ability of evaporative preconcentration of silver nanoparticles.

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“…This is exemplified in recent exercises of energy harvesting using solid structures. , In returning to the case with sessile drops, Chaudhury and Goohpattader demonstrated that drops rolling down a surface with asperities lithographically produced using fibrils with well-defined lengths, cross sections, and spacing could elicit resonance behavior . More recently, an arguably more practical approach was achieved by having the liquid body on a stationary tip coming in contact with a rotating SH drum such that resonance is maintained primarily from stochastic stick–slip events between the liquid and SH surface …”

Section: Introductionmentioning

confidence: 99%

“…23 More recently, an arguably more practical approach was achieved by having the liquid body on a stationary tip coming in contact with a rotating SH drum such that resonance is maintained primarily from stochastic stick− slip events between the liquid and SH surface. 24 Although drops can easily slide down surfaces because of the action of gravity, schemes such as the substrate wetting transformation and air perturbation have been shown to achieve motion up inclines notwithstanding gravity. 12,25 The ability to control the speed of transport of the drop, however, is not possible using these schemes.…”

Section: ■ Introductionmentioning

confidence: 99%

Linear Stepper Actuation Driving Drop Resonance and Modifying Hysteresis

et al. 2016

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In this work, 2 μL water drops are placed on substrates that are created to have a circular hydrophilic region bounded by superhydrophobicity so that they exhibit high contact angles. When the substrate is translated by a linear stepper actuator, the random force components present in the actuator are shown to cause the drop to rock resonantly. When the substrate is translated downward at inclination angles of up to 6° with respect to the horizontal, the contact angle hysteresis increases progressively to a limiting condition. When the substrate is moved up at inclined angles, alternatively, the contact angle hysteresis increases initially to the limiting condition before it is progressively restored to its static state. These behaviors are accounted for by the reversible micro-Cassie to Wenzel wetting state transformations that are made possible by the hierarchical microscale and nanoscale structures present in the superhydrophobic regions.

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Liquid-body resonance while contacting a rotating superhydrophobic surface

Cited by 5 publications

References 37 publications

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Simultaneous Multidrop Creation with Superhydrophobic Wells for Field Environmental Sensing of Nanoparticles

Linear Stepper Actuation Driving Drop Resonance and Modifying Hysteresis

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