Micro Droplet Transfer between Superhydrophobic Surfaces via a High Adhesive Superhydrophobic Surface

Ishii, Daisuke; Yabu, Hiroshi; Shimomura, Masatusgu

doi:10.1007/978-3-642-11721-3_10

Cited by 5 publications

(6 citation statements)

References 9 publications

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“…The metal domes have good affinity for water and, therefore, affect the adhesion properties of water microdroplets on the hybrid surface. 17 The sliding angle, which is a measure of the adhesion strength of a droplet, was investigated to elucidate the dependence of adhesion strength on position along the substrate. In Figure 3a, the sliding angles of water droplets of various masses are plotted versus position d along the hybrid surface having a gradient in the number density of metal domes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Invisible Gates for Moving Water Droplets: Adhesive Force Gradients on a Biomimetic Superhydrophobic Surface

Ishii

Shimomura

2013

Chem. Mater.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Invisible Gates for Moving Water Droplets: Adhesive Force Gradients on a Biomimetic Superhydrophobic Surface

Ishii

Shimomura

2013

Chem. Mater.

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“…The sample flow channel was fabricated to accommodate multiple samples with water and air in various flow conditions, where drag is characterized by measuring pressure drop, and the interactions between vortices and the riblet surfaces were also given . In section above, the tunable wettability is feasible, also, the high adhesion surface, middle adhesion, and low adhesion surfaces were adopted by researchers to achieve no mass loss transfer, and the schematic is shown in Figure .…”

Section: Applicationmentioning

confidence: 99%

Section: Applicationmentioning

confidence: 99%

Wetting Models and Working Mechanisms of Typical Surfaces Existing in Nature and Their Application on Superhydrophobic Surfaces: A Review

Jin

Deng

et al. 2017

Adv. Mater. Interfaces

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decades, researchers have shown great interests in bionics, which was a new multidisciplinary subject inspired by biological characteristics and features to imitate it to build technology devices. [1] With the rise of biomimetic biomaterial researches, a lot of attention was paid on the observation of living organism, especially on plant leaves, such as lotus, rice, taro leaves, etc. [2] As the development of scanning electron microscope (SEM), a wealth of data dealing with SEM of plant surface has been published since 1960s. [3] The cuticular structure was investigated with regard to function, and substances that were secreted onto the cuticle had great effects on the surface properties, while intracuticular waxes were the main barrier to wettability. [4] Some kinds of special wettability like superhydrophobicity and superhydrophilicity were also found in other surfaces, such as self-cleaning lotus leaf, [5] hydrophilicity of red rose petals, [6,7] the anisotropic dewetting behavior on rice leaf, [8,9] hydrophobicity of shark skin, [10] gecko toe, [11] insect wings, [12] etc., and striking superhydrophobic force provided by a water strider's legs, [13] and they were all related to the unique microstructures on their surface. In fact, the special wettability of surfaces is attributed to the interaction of both the surface microstructures and surface covers. As the development and progress of the observation device, smaller nanosized structures were found on the microstructure, and better properties of multiscale hierarchical structure was shown then. [14] Wetting is a phenomenon that solid interface was transferred from solid-gas interface to solid-liquid interface, wettability was a kind of ability that a liquid could be unfolded on one solid surface. The wettability of surface could be characterized by contact angle (CA) of interface. Sliding angle (SA) and contact angle hysteresis were introduced to evaluate the highly valued superhydrophobicity and superhydrophilicity of surfaces. Superhydrophilicity was defied as that of CA was smaller than 5°, superhydrophobicity was defied as that of CA was greater than 150°, as well as a really small sliding angle. It is worth noting that many researchers applied themselves to excavate the theories under the phenomena. Young's equation, Wenzel equation, and Cassie-Baxter equation [15,16] were the representations of hundreds years of research results. Improving and developing Surfaces of plants and animals are evolved to optimal states to accommodate environments better after billions of years of natural selection. As the development of further study on bionics, surfaces with special wetting properties in nature are discovered, extremely related to the micro-/nanostructures on surface. The wetting models and wetting mechanism of several surfaces in nature are investigated, followed by lifting the veil of superhydrophobic field. Various facile, effective, and convenient methods for fabricating superhydrophobic surfaces are obtained and optimized in scientific research and ...

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“…2 Such sticky superhydrophobic surfaces have potential applications in liquid transportation, 11 ink-jet printing, 12 and microuidic devices. 13 Therefore, these superhydrophobic surfaces are entirely different in nature and have received growing interests in distinct application elds. However, the existing researches on these pinning phenomena are not consistent and the mechanism of the pinning effect has not been clearly understood.…”

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Pinning mechanism of advancing sessile droplet on superhydrophobic surfaces

Xia

Lei

et al. 2014

RSC Adv.

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This study explores the working mechanism and the influence factor of the pinning effect of advancing sessile droplets on micropillared superhydrophobic surfaces. Our experimental result reflects that the pinning effect of the advancing droplet is determined by a new parameter, which is named the local triple-phase contact line (LTCL).The pinning force is proved proportionate to the maximal value of the LTCL attainable along the actual droplet boundary. Meanwhile, a theoretical model is built to explain the pinning phenomena on various liquid/solid interfaces.Superhydrophobic surfaces, exhibiting high water contact angles (>150 ), have attracted a lot of interest for their extreme non-wetting properties. 1-5 A droplet on a superhydrophobic surface can be either slippery or sticky, which is differentiated by the pinning phenomena of the moving droplet on the surface. On a slippery surface, a water droplet rolls off the surface once it is tilted. 1 Such water repellent properties have found applications in self-cleaning, 6 drag reduction, 7 antiicing, 8 anti-biofouling 9 and anti-corrosion. 10 In contrast to the slippery surface, the water droplet sitting on the sticky ones does not roll off even if the surface is turned upside down. 2 Such sticky superhydrophobic surfaces have potential applications in liquid transportation, 11 ink-jet printing, 12 and microuidic devices. 13 Therefore, these superhydrophobic surfaces are entirely different in nature and have received growing interests in distinct application elds. However, the existing researches on these pinning phenomena are not consistent and the mechanism of the pinning effect has not been clearly understood. 14-20 Some researchers claimed that the solid fraction is the dominant factor 15,16 while some others believed that the triple-phase contact line (TCL) is the dominant factor instead. [18][19][20] Settling this disagreement and determining the controlling mechanism of the phenomena will contribute greatly to the scientic world. In this study by comparing and analyzing the difference between the advancing contact angles and the predicted Cassie angles, 21 we were able to gain a deeper understanding of pinning mechanism which could be used to predict the pinning phenomena on superhydrophobic surfaces. Fig. 1 shows the patterns fabricated by us. The micropillar patterns had the same pitch size (40 mm), but different side lengths of 4 mm, 8 mm, 16 mm and 24 mm. The solid fraction of these samples varied from 0.01, 0.04, and 0.16 to 0.36, denoted as S0.01, S0.04, S0.16 and S0.36, respectively. A at silicon substrate was tested as a control experiment, and denoted as S1.00.From the observation of apparent contact angles measurements by the sessile drop method (Method section for details), the droplet boundary was xed on the substrate in the initial Fig. 1 Scanning electron microscopy images of the micropillared superhydrophobic surfaces. The solid fraction varies from (a) 0.01, (b) 0.04, (c) 0.16 to (d) 0.36. All scale bars are 40 mm.

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Micro Droplet Transfer between Superhydrophobic Surfaces via a High Adhesive Superhydrophobic Surface

Cited by 5 publications

References 9 publications

Invisible Gates for Moving Water Droplets: Adhesive Force Gradients on a Biomimetic Superhydrophobic Surface

Invisible Gates for Moving Water Droplets: Adhesive Force Gradients on a Biomimetic Superhydrophobic Surface

Wetting Models and Working Mechanisms of Typical Surfaces Existing in Nature and Their Application on Superhydrophobic Surfaces: A Review

Pinning mechanism of advancing sessile droplet on superhydrophobic surfaces

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