Coalescence of droplets on micro-structure patterned hydrophobic planar solid surfaces

Zhu, Guiping; Fan, Hui; Huang, Hulin; Duan, Fei

doi:10.1039/c7ra03323k

Cited by 11 publications

(4 citation statements)

References 39 publications

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“…There are so many studies that have focused on the effect of surface structures. Zhu et al 23 investigated the coalescence dynamics of droplets on microtextured surfaces decorated with circular pillared structures that have different sizes (i.e., different intervals and diameters). It was found that the substrates would exhibit stronger hydrophobicity when the interval of pillars is large, and thus accelerate the coalescing process.…”

Section: ■ Introductionmentioning

confidence: 99%

Controllable Coalescence Dynamics of Nanodroplets on Textured Surfaces Decorated with Well-Designed Wrinkled Nanostructures: A Molecular Dynamics Study

Zhang

2021

Langmuir

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The control of coalescence and motion of droplets play a significant role in advanced technology and our daily life, and one of the most important approaches is surface design. Here, the microtextured surfaces decorated with wrinkled substrates are designed and studied for coalescence behaviors. The simulation results show that the coalescence speed would be slower on such surfaces due to the downward movement of the droplets induced by the penetration of atoms into the grooves that delays their movement along the coalescence direction, which is considered as a restriction effect. With the increase of the angles and the interval distance of wrinkled structures, the coalescence time becomes longer and the coalescing process becomes unfavorable, resulting from the enhanced restriction effect. More importantly, a composite substrate possessing the original and sub-wrinkled structures has been designed to tune the coalescence dynamics. The results of this work may not only help shed light on understanding the coalescence behaviors on the wrinkled substrates but also propose a feasible method for controlling the liquid coalescence behavior, which is expected to provide some useful implications for practical applications.

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Section: ■ Introductionmentioning

confidence: 99%

Controllable Coalescence Dynamics of Nanodroplets on Textured Surfaces Decorated with Well-Designed Wrinkled Nanostructures: A Molecular Dynamics Study

Zhang

2021

Langmuir

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“…Since then, numerous papers on sessile drop coalescence have appeared. Topics of investigation have included power law growth of the liquid bridge after coalescence initiation [17,18,19,20,21,22,23], overall shape evolution [7,24,25,26,27,28,29,30], and long-time contact line relaxation dynamics [31,32,33,34,35]. Following the 2009 discovery of self-propelled dropwise condensate removal on superhydrophobic surfaces [36,37], a majority of these studies have explored coalescence-induced out-of-plane drop jumping [38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60 For their utility in interpreting experimental observations, computational fluid dynamics simulations of sessile drop coalescence have also become popular over the last decade…”

Section: Introductionmentioning

confidence: 99%

Sweeping by Sessile Drop Coalescence

Ludwicki,

Steen

2020

Preprint

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During coalescence of liquid drops contacting a solid, the liquid sweeps wetted and solid-projected areas. The extent of sweeping dictates the performance of devices such as self-cleaning surfaces, antifrost coatings, water harvesters, and dropwise condensers. For these applications, weakly-and non-wetting solid substrates are preferred as they enhance drop dynamical behavior. Accordingly, our coalescence studies here are restricted to drops with contact angle 90°≤ θ0 ≤ 180°. Binary sessile drop coalescence is the focus, with volume of fluid simulations employed as the primary tool. The simulations, which incorporate a Kistler dynamic contact angle model, are first validated against three different experimental substrate systems and then used to study the influence of solid wettability on sweeping by modifying θ0. With increasing θ0 up to 150°, wetted and projected swept areas both increase as drop center of mass heightens. For θ0 ≥ 150°, coalescence-induced drop jumping occurs owing to the decreasing wettability of the substrate and a focusing of liquid momentum due to the symmetry-breaking solid. In this regime, projected swept area continues to increase with θ0 while wetted swept area reaches a maximum and then decreases. The sweeping results are interpreted using the mechanical energy balance from hydrodynamic theory and also compared to free drop coalescence.

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“…Microsized droplet manipulations such as droplet storage, − transfer, − and mixing − have attracted considerable attention due to their great potential applications in high throughput cell screening, − biochemical synthesis, − molecular sensing, , and other lab-on-a-chip devices. , For instance, spherical droplet arrays pinned on a solid surface can serve as miniature vessels to culture cells for high throughput cell transfection and drug screening. − In comparison with microplate technology, the above methods can reduce reagents and cell consumption by 15000 times . Seeding molecules for detection into the droplet and enriching the droplet by controlled volatilization can greatly increase the molecular target concentration in the droplet, increase the reaction probability of the probe and target, and thus improve the detection accuracy of the molecular target.…”

Section: Introductionmentioning

confidence: 99%

Droplet Mechanical Hand Based on Anisotropic Water Adhesion of Hydrophobic–Superhydrophobic Patterned Surfaces

et al. 2019

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Superhydrophobic copper surfaces patterned with non-round hydrophobic areas were fabricated by a combination of through-mask chemical oxidation and fluorocarbon film deposition techniques. The anisotropic sliding resistance of droplets on typical non-round hydrophobic patterns such as semicircle, V-shape, and line segment hydrophobic patterns was observed. The dependence of sliding anisotropy on the pattern shape and dimensions was investigated. Results showed that the experimental sliding resistance was in good agreement with the calculated data using a classical drag–resistance model (Furmidge equation). By taking advantage of the anisotropic sliding resistance, these patterned surfaces can be used as droplet mechanical hands to capture, transfer, mix, and release in situ micro droplets by simply moving the surfaces in different directions. A droplet pinned on a non-round hydrophobic pattern can be captured by lifting a surface with another non-round hydrophobic pattern in a large-sliding-resistance direction after touching it, while the captured droplet can be released in situ with nearly no mass loss by horizontally moving the surface in the low-sliding-resistance direction. The lossless droplet manipulations using hydrophobic/superhydrophobic patterned surfaces have advantages of being low in cost and easy to operate and may have great promising applications to high throughput drug screening, molecular detection, and other lab-on-chip devices.

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Coalescence of droplets on micro-structure patterned hydrophobic planar solid surfaces

Cited by 11 publications

References 39 publications

Controllable Coalescence Dynamics of Nanodroplets on Textured Surfaces Decorated with Well-Designed Wrinkled Nanostructures: A Molecular Dynamics Study

Controllable Coalescence Dynamics of Nanodroplets on Textured Surfaces Decorated with Well-Designed Wrinkled Nanostructures: A Molecular Dynamics Study

Sweeping by Sessile Drop Coalescence

Droplet Mechanical Hand Based on Anisotropic Water Adhesion of Hydrophobic–Superhydrophobic Patterned Surfaces

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