Bioinspired inner microstructured tube controlled capillary rise

Li, Chuxin; Dai, Haoyu; Gao, Can; Wang, Ting; Dong, Zhichao; Jiang, Lei

doi:10.1073/pnas.1821493116

Cited by 117 publications

(108 citation statements)

References 41 publications

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“…Therefore, the PTGA improves drainage efficiency by reducing water retention and threshold drainage time. The understanding of this drainage mechanism from leaf apex and architecture drip tile can be used to design drainage facilities and solve problems in printing and open-air fluidic systems (34)(35)(36) that are currently faced.…”

Section: Reduced Water Drainage Retention On Pendulous Triangular Gromentioning

confidence: 99%

Apex structures enhance water drainage on leaves

Wang

Dai

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The rapid removal of rain droplets at the leaf apex is critical for leaves to avoid damage under rainfall conditions, but the general water drainage principle remains unclear. We demonstrate that the apex structure enhances water drainage on the leaf by employing a curvature-controlled mechanism that is based on shaping a balance between reduced capillarity and enhanced gravity components. The leaf apex shape changes from round to triangle to acuminate, and the leaf surface changes from flat to bent, resulting in the increase of the water drainage rate, high-dripping frequencies, and the reduction of retention volumes. For wet tropical plants, such as Alocasia macrorrhiza, Gaussian curvature reconfiguration at the drip tip leads to the capillarity transition from resistance to actuation, further enhancing water drainage to the largest degree possible. The phenomenon is distinct from the widely researched liquid motion control mechanisms, and it offers a specific parametric approach that can be applied to achieve the desired fluidic behavior in a well-controlled way.

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Section: Reduced Water Drainage Retention On Pendulous Triangular Gromentioning

confidence: 99%

Apex structures enhance water drainage on leaves

Wang

Dai

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…2) The poor wettability and large molecular weight of polymer additives restrict the ejecting process during inkjet printing. 3) Surfactant additives can promote drop spreading in a static state owing to the reduced surface tension (γ); however, the low surface tension increases the instability of the impacting drop and leads to drop splashing with satellite droplets, according to the Kelvin–Helmholtz instability, k max ∼ 2ρ a U r 2 /3γ (ρ a is the air density). It is therefore a great challenge for uniform shape spreading on superhydrophobic surfaces without any loss of the drops.…”

mentioning

confidence: 99%

“…When the pure water drop impacts the superhydrophobic surface, the drop undergoes spread, retraction, and relaxation (Figure f). Air trapped at the expanding edge causes the Kelvin–Helmholtz instability and corresponding breakup of spreading lamella, which triggers the drop splash during the impact‐spread process . Then, the high recoiling velocity due to the low friction between water and the superhydrophobic substrate during retraction leads to the violent drop fragmentation.…”

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confidence: 99%

Uniform Spread of High‐Speed Drops on Superhydrophobic Surface by Live‐Oligomeric Surfactant Jamming

et al. 2019

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self-cleaning and antifouling ability for repelling the deposition of other materials and liquid confining properties for enhancing printing resolution and avoiding coffee-ring effects. [13] However, inertial water drops impacting superhydrophobic surfaces can bounce off quickly or splash violently. [14][15][16][17][18][19][20][21][22][23] Undesired rebound and splash cause material waste [24] and weaken the related performance and efficiency. Many attempts have been conducted to promote water drop spreading on hydrophobic surfaces by using polymers [1,23,[25][26][27][28] or surfactants. [22,[29][30][31][32] However, these two methods still have drawbacks for achieving drop deposition, not to mention uniform spreading: 1) Polymer additives can delay drop retraction but leave drops with hemispherical shape and nonuniform material distribution on the hydrophobic substrate.2) The poor wettability and large mole cular weight of polymer additives restrict the ejecting process during inkjet printing. 3) Surfactant additives can promote drop spreading in a static state owing to the reduced surface tension (γ); [33] however, the low surface tension increases the instability of the impacting drop and leads to drop splashing with satellite droplets, according to the Kelvin-Helmholtz instability, [34] k max ∼ 2ρ a U r 2 /3γ (ρ a is the air density). It is therefore a great challenge for uniform shape spreading on superhydrophobic surfaces without any loss of the drops. Here, we show a new and simple strategy for uniform round-shape drop spreading on superhydrophobic surfaces after high-speed impact, up to 5.0 m s −1 , by utilizing live-oligomeric surfactant jamming, diethylenetriamine/sodium dodecyl sulfate (triamine/SDS). The live-oligomeric surfactant, which noncovalently constructed by SDS and triamine through electrostatic interaction, has a dynamic equilibrium between monomer surfactant and oligomeric surfactant. Figure 1 shows the contrast spread dynamics of a liveoligomeric surfactant drop and other drops impacting superhydrophobic surfaces at an impacting velocity (U ) of 2.42 m s −1 from side and bottom views (Movie S1, Supporting Information). The diameter (D 0 ) of pure water and the surfactant drops is ≈2.25 and 1.90-2.00 mm, respectively (Figure S1, Supporting Information for experimental setup). The Weber number (We), We = ρDV 2 /γ, of water, SDS, N2C3/SDS, triamine/SDS, and 12-3-12-3-12 is 182. 68, 295.29, 358.29, 383.00, and 292.29, respectively. The superhydrophobic surface [35] composed of random micro-nanostructures of typical size and spacing of Inkjet printing of water-based inks on superhydrophobic surfaces is important in high-resolution bioarray detection, chemical analysis, and highperformance electronic circuits and devices. Obtaining uniform spreading of a drop on a superhydrophobic surface is still a challenge. Uniform round drop spreading and high-resolution inkjet printing patterns are demonstrated on superhydrophobic surfaces without splash or rebound after high-speed impacting by introducing...

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“…5a). [60][61][62][63] This enhanced capillary effect can be explained by a capillary rise at the corner formed by two vertical plates making a small angle ( Fig. 5b).…”

Section: Bio-mimetic Wedge Corner Structuresmentioning

confidence: 99%

“…The experiments conrmed that in a gradient wedge (a 1 s a 2 ), the capillary rise will be higher than the case of a xed wedge angle. 59,61 Experimental and numerical studies have characterized the directional transportation of these unique structures in terms of surface wettability, as well as the viscosity and surface tension of the liquid. [66][67][68][69][70] In 2017, Chen et al 6 also fabricated bio-inspired unidirectional liquid spreading surfaces using inclined UV exposure of SU-8 photoresist.…”

Section: Bio-mimetic Wedge Corner Structuresmentioning

confidence: 99%