A superhydrophobic manhole for drops

Chung, Dwayne Chung Kim; Huynh, So Hung; Wang, Shufen; Jiang, Xuchuan; Liew, Oi Wah; Muradoglu, Murat; Ng, Tuck Wah

doi:10.1039/c6ta09459g

Cited by 17 publications

(12 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This results in two outcomes. In the first, the liquid body falls completely from the hole (as per the manhole effect previously reported 12 ). In the other, depicted in the remaining image–time sequences of Figure 9, the overhanging component starts to contract progressively.…”

Section: Resultsmentioning

confidence: 53%

“…These findings have important implications in the reported use of evaporative preconcentration to assist in the detection of low concentrations of nanoparticles in solutions while limiting the effect of contamination (from other stray particulates in the environment) using SH substrates. 12 In using SH mesh substrates with holes, it is possible to conduct this with multiple drops, combining those that have fallen off (the liquid drop fall-off assured because cross-sectional pinning area being minimized), and then repeating the process. This will result in a final drop that will have a much higher concentration of nanoparticles available for detection.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Chung¹,

Huynh²,

Katariya³

et al. 2017

ACS Omega

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Drops on a Superhydrophobic Hole Hanging On under Evaporation

Chung¹,

Huynh²,

Katariya³

et al. 2017

ACS Omega

Self Cite

View full text Add to dashboard Cite

show abstract

“…Such wetting behaviors are governed by two-phase (liquid and air) and three-phase (liquid, solid, and air) interactions. 17 Recently, a “manhole” preconcentration approach 18 based on evaporation 19 and suitable for field application was reported. To attain higher detection sensitivity, the preconcentration process is performed by creating multiple drops where volume reduction is achieved in successive stages (see Figure 1A).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…They were first observed in the flora and fauna of nature , and now replicable via various chemical treatment methods. , Liquids placed on SH surfaces are characterized by the presence of a thin film of air (plastron), where sessile drops exhibit high contact angles (>150°) at the three phase contact line . The strong degree of water repellence permits large sessile drops to remain on the surface even with a hole underneath it. , The premise of high drag reduction in flows remains an enduring motivation for using SH surfaces. , …”

Section: Introductionmentioning

confidence: 99%

“…8 The strong degree of water repellence permits large sessile drops to remain on the surface even with a hole underneath it. 9,10 The premise of high drag reduction in flows remains an enduring motivation for using SH surfaces. 11,12 In this work, we demonstrate the capability of hydrophilic and superhydrophobic substrates that have holes of sizes ranging from 1.0−2.0 mm on them to act as valves, allowing the automatic filling and discharge of water from a receptacle controlled only by the amount of hydrostatic pressure present.…”

Section: ■ Introductionmentioning

confidence: 99%

Millimeter-Sized Hole Damming

et al. 2017

Self Cite

View full text Add to dashboard Cite

Valves used to control liquid filling and draining processes from storage typically need to be actuated. Here, we show that similar flow enabling and restricting operations can be achieved through millimeter scale holes that function according to the amount of hydrostatic pressure applied without any other intervention. This phenomena is exhibited using receptacles where the base is made of either a hydrophilic or superhydrophobic substrate with hole sizes ranging from 1.0-2.0 mm. The construction is such that the drainage flow velocities are of the same order in both substrates and follow Torricelli's law trends. Nevertheless, the primary mechanisms responsible for resisting the onset of flow in each substrate are different; nonbreaching of the advancing contact angle threshold in the former, and stable maintenance of an elastic-like deformation of the liquid-gas interface that is connected to the surrounding plastron in the latter. These differences are demonstrated using an upward jet of water delivered to the orifice, where a discharging flow from the hydrophilic base occurred before the threshold hydrostatic pressure condition was attained, while liquid from the jet is subsumed into the liquid body of the receptacle with the superhydrophobic base without any leakage. These findings portend advantages in simplicity and robustness for a myriad of liquid-related processes.

show abstract

A superhydrophobic manhole for drops

Cited by 17 publications

References 25 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

Millimeter-Sized Hole Damming

Contact Info

Product

Resources

About