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Lei Jiang - One of the best experts on this subject based on the ideXlab platform.
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rose petals with a novel and steady Air Bubble pinning effect in aqueous media
Soft Matter, 2012Co-Authors: Jingming Wang, Lei Jiang, Qinglin Yang, Mingchao Wang, Chun WangAbstract:Many well-known natural superhydrophobic surfaces exhibit unique characteristics when immersed in the aqueous medium. In the present paper, the phenomenon of the steady pinning effect of Air Bubbles on a rose petal with a combination of hierarchical rough structures (i.e., micropapillae and nanofolds) is described. The pinning force of a 2 μL Air Bubble is ca. 101.2 μN, and the critical flow velocity of water leading the three-phase contact line (TPCL) to slide is as quick as 124.7 mm s−1. The artificial rose petal surface was prepared from polydimethlsiloxane (PDMS) by a casting technique. It has the same nanofolds and micropapillae as the rose petal surface, and shows a similar Air Bubble pinning effect. The pinning force and the critical flow velocity of the artificial rose petal surface are 140.7 μN and 156.7 mm s−1, respectively. Smooth and rough PDMS films with an ordered nanostructure or patterned microstructure are utilized to study the contribution of the micro/nano hierarchical structures to the Air Bubble pinning effect. Particularly, the facility that the captured Air pockets in the nanostructure of the rose petals (ca. 500–600 nm in width on each micropapilla tip) coalesce with the Air Bubble is shown. The process where a periodic array of microstructures (diameter: 16 μm, height: 7 μm) construct “absorbed” islands to avoid the coalescence between the adjacent Air pockets on the nanofolds is demonstrated as well. The important roles of the size and distribution of the microstructure of the rose petal in the Air Bubble pinning process are highlighted. This steady pinning effect induced on superhydrophobic surfaces with micro/nano hierarchical rough structures should spark further theoretical study on other Bubble-related interfacial phenomena and should open a new avenue for their application in industrial processes, including the cleaning of boats contaminated by plankton and oil, reduction of drag friction on ships and submarine hulls, and the foaming control process.
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Air Bubble bursting effect of lotus leaf.
Langmuir, 2009Co-Authors: Jingming Wang, Jin Zhai, Yongmei Zheng, Lei JiangAbstract:In this paper, a phenomenon of Air Bubbles quickly bursting within several milliseconds on a “self-cleaning” lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar Air Bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of Air Bubble bursting. Air Bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, Air Bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect Air Bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae...
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Air Bubble bursting effect of lotus leaf
Langmuir, 2009Co-Authors: Jingming Wang, Jin Zhai, Yongmei Zheng, Lei Jiang, Fuqiang NieAbstract:In this paper, a phenomenon of Air Bubbles quickly bursting within several milliseconds on a "self-cleaning" lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar Air Bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of Air Bubble bursting. Air Bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, Air Bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect Air Bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae, the width and spacing were significant for Air Bubble bursting. An original model was proposed to further evaluate the reason why the micro/nano hierarchical rough structures had an excellent Air Bubble bursting effect, and the validity of the model was theoretically demonstrated.
Kirti Chandra Sahu - One of the best experts on this subject based on the ideXlab platform.
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transition of Bubble motion from spiralling to zigzagging a wake controlled mechanism with a transverse magnetic field
International Journal of Multiphase Flow, 2021Co-Authors: Jie Zhang, Kirti Chandra SahuAbstract:Abstract We investigate the dynamics of a millimetre-sized Air Bubble rising in a liquid due to buoyancy under the influence of a magnetic field applied in a direction transverse to the Bubble motion by conducting three-dimensional numerical simulations. The path and trajectory of the Air Bubble are examined by varying the strength of the transverse magnetic field. In the absence of a magnetic field, it is well known that under certain conditions a tiny Air Bubble undergoes spiralling motion due to its shape deformation and vortex shedding in the wake region. It is shown here that the spiralling motion of an Air Bubble observed without magnetic field transforms into a purely zigzagging motion under an applied transverse magnetic field. To understand the mechanism, we analyse the evolution of the wake vortices and forces experienced by the Bubble in the presence of a transverse magnetic field. It is found that the twisted double-threaded vortices observed in a spiralling Bubble in the absence of a magnetic field appear to rotate perpendicularly to the applied magnetic field across the vertical axis, thereby making the Bubble shift its trajectory from spiralling to zigzagging. By calculating the lift and drag forces acting on the Bubble, it is shown that how these forces acting on the Bubble contribute to the vortex shedding patterns. Thus, the present study demonstrates the mechanism to control the trajectory of an Air Bubble under the application of a magnetic field.
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shapes and paths of an Air Bubble rising in quiescent liquids
Physics of Fluids, 2017Co-Authors: D. M. Sharaf, A. R. Premlata, Manoj Kumar Tripathi, Badarinath Karri, Kirti Chandra SahuAbstract:Shapes and paths of an Air Bubble rising inside a liquid are investigated experimentally. About three hundred experiments are conducted in order to generate a phase plot in the Galilei and Eotvos numbers plane, which separates distinct regimes in terms of Bubble behaviour. A wide range of the Galilei and Eotvos numbers are obtained by using aqueous glycerol solutions of different concentrations as the surrounding fluid and by varying the Bubble size. The dynamics are investigated in terms of shapes, topological changes, and trajectories of the Bubbles. Direct numerical simulations are conducted to study the Bubble dynamics, which show excellent agreement with the experiments. To the best of our knowledge, this is the first time an experimentally obtained phase plot showing the distinct behaviour of an Air Bubble rising in a quiescent medium is reported for such a large range of Galilei and Eotvos numbers.
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Shapes and paths of an Air Bubble rising in quiescent liquids
Physics of Fluids, 2017Co-Authors: D. M. Sharaf, A. R. Premlata, Manoj Kumar Tripathi, Badarinath Karri, Kirti Chandra SahuAbstract:Shapes and paths of an Air Bubble rising inside a liquid are investigated experimentally. About three hundred experiments are conducted in order to generate a phase plot in the Galilei and Eotvos numbers plane, which separates distinct regimes in terms of Bubble behaviour. A wide range of the Galilei and Eotvos numbers are obtained by using aqueous glycerol solutions of different concentrations as the surrounding fluid, and by varying the Bubble size. The dynamics is investigated in terms of shapes, topological changes and trajectories of the Bubbles. Direct numerical simulations are conducted to study the Bubble dynamics, which show excellent agreement with the experiments. To the best of our knowledge, this is the first time an experimentally obtained phase plot showing the distinct behaviour of an Air Bubble rising in a quiescent medium is reported for such a large range of Galilei and Eotvos numbers.
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dynamics of an Air Bubble rising in a non newtonian liquid in the axisymmetric regime
Journal of Non-newtonian Fluid Mechanics, 2017Co-Authors: A. R. Premlata, Manoj Kumar Tripathi, Badarinath Karri, Kirti Chandra SahuAbstract:Abstract An Air Bubble rising in a non-Newtonian fluid (shear thinning/thickening) has been numerically studied using a volume-of-fluid (VoF) approach in the axisymmetric regime. The governing equations consist of mass and momentum conservation, coupled to an equation for the volume fraction of the non-Newtonian fluid, which is modelled using the Carreau–Yasuda model. The solver is validated extensively by performing grid convergence test and comparing with the earlier studies in the literature. A parametric study is conducted by varying the shear-thinning/thickening tendency of the surrounding fluid for different Gallilei and Eotvos numbers. The effect of these parameters is quantified in terms of their influence on the aspect ratio of the Bubble, the position of the center of gravity and the Bubble shape as these evolve over time. We found that increasing the shear thinning tendency increases the rise velocity, and reduces the deformations of the Bubble. The deformation of the Bubble is also enhanced for higher Gallilei number and low Eotvos number.
David M Eckmann - One of the best experts on this subject based on the ideXlab platform.
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Air Bubble Contact with Endothelial Cells Causes a Calcium-Independent Loss in Mitochondrial Membrane Potential
2016Co-Authors: Peter Sobolewski, Judith K, David M EckmannAbstract:Objective: Gas microembolism remains a serious risk associated with surgical procedures and decompression. Despite this, the signaling consequences of Air Bubbles in the vasculature are poorly understood and there is a lack of pharmacological therapies available. Here, we investigate the mitochondrial consequences of Air Bubble contact with endothelial cells. Methods and Results: Human umbilical vein endothelial cells were loaded with an intracellular calcium indicator (Fluo-4) and either a mitochondrial calcium indicator (X-Rhod-1) or mitochondrial membrane potential indicator (TMRM). Contact with 50–150 mm Air Bubbles induced concurrent rises in intracellular and mitochondrial calcium, followed by a loss of mitochondrial membrane potential. Pre-treating cells with 1 mmol/L ruthenium red, a TRPV family calcium channel blocker, did not protect cells from the mitochondrial depolarization, despite blocking the intracellular calcium response. Mitigating the interactions between the Air-liquid interface and the endothelial surface layer with 5 % BSA or 0.1 % Pluronic F-127 prevented the loss of mitochondrial membrane potential. Finally, inhibiting protein kinase C-a (PKCa), with 5 mmol/L Gö6976, protected cells from mitochondrial depolarization, but did not affect the intracellular calcium response. Conclusions: Our results indicate that Air Bubble contact with endothelial cells activates a novel, calcium-independent, PKCa-dependent signaling pathway, which results in mitochondrial depolarization. As a result, mitochondrial dysfunction is likely to be a key contributor to the pathophysiology of gas embolism injury. Further, this connection between th
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Air Bubble contact with endothelial cells causes a calcium independent loss in mitochondrial membrane potential
Biophysical Journal, 2013Co-Authors: Peter Sobolewski, Judith Kandel, David M EckmannAbstract:Gas microembolism remains a serious risk associated with surgical procedures and decompression illness. Despite this, the signaling consequences of Air Bubbles in the vasculature are poorly understood and there is a lack of pharmacological therapies available. Here, we investigate the mitochondrial consequences of Air Bubble contact with endothelial cells. Methods and Human umbilical vein endothelial cells were loaded with an intracellular calcium indicator (Fluo-4) and either a mitochondrial calcium indicator (X-Rhod-1) or mitochondrial membrane potential indicator (TMRM). Contact with 50-150 μm Air Bubbles induced concurrent rises in intracellular and mitochondrial calcium, followed by a loss of mitochondrial membrane potential. Pre-treating cells with 1 μmol/L ruthenium red (RuR), a TRPV family calcium channel blocker, did not protect cells from the mitochondrial depolarization, despite blocking the intracellular calcium response. Mitigating the interactions between the Air-liquid interface and the endothelial surface layer with 5% BSA or 0.1% Pluronic F-127 prevented the loss of mitochondrial membrane potential. Finally, inhibiting protein kinase C-α (PKCα), with 5 μmol/L Go6976, protected cells from mitochondrial depolarization, but did not affect the intracellular calcium response. Our results indicate that Air Bubble contact with endothelial cells activates a novel, calcium-independent, PKCα-dependent signaling pathway, which results in mitochondrial depolarization. As a result, mitochondrial dysfunction is likely to be a key contributor to the pathophysiology of gas embolism injury. Further, this connection between the endothelial surface layer and endothelial mitochondria may also play an important role in vascular homeostasis and disease.
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Air Bubble contact with endothelial cells causes a calcium independent loss in mitochondrial membrane potential
PLOS ONE, 2012Co-Authors: Peter Sobolewski, Judith Kandel, David M EckmannAbstract:Objective Gas microembolism remains a serious risk associated with surgical procedures and decompression. Despite this, the signaling consequences of Air Bubbles in the vasculature are poorly understood and there is a lack of pharmacological therapies available. Here, we investigate the mitochondrial consequences of Air Bubble contact with endothelial cells. Methods and results Human umbilical vein endothelial cells were loaded with an intracellular calcium indicator (Fluo-4) and either a mitochondrial calcium indicator (X-Rhod-1) or mitochondrial membrane potential indicator (TMRM). Contact with 50-150 µm Air Bubbles induced concurrent rises in intracellular and mitochondrial calcium, followed by a loss of mitochondrial membrane potential. Pre-treating cells with 1 µmol/L ruthenium red, a TRPV family calcium channel blocker, did not protect cells from the mitochondrial depolarization, despite blocking the intracellular calcium response. Mitigating the interactions between the Air-liquid interface and the endothelial surface layer with 5% BSA or 0.1% Pluronic F-127 prevented the loss of mitochondrial membrane potential. Finally, inhibiting protein kinase C-α (PKCα), with 5 µmol/L Go6976, protected cells from mitochondrial depolarization, but did not affect the intracellular calcium response. Conclusions Our results indicate that Air Bubble contact with endothelial cells activates a novel, calcium-independent, PKCα-dependent signaling pathway, which results in mitochondrial depolarization. As a result, mitochondrial dysfunction is likely to be a key contributor to the pathophysiology of gas embolism injury. Further, this connection between the endothelial surface layer and endothelial mitochondria may also play an important role in vascular homeostasis and disease.
Hongbo Zeng - One of the best experts on this subject based on the ideXlab platform.
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interaction mechanisms between Air Bubble and molybdenite surface impact of solution salinity and polymer adsorption
Langmuir, 2017Co-Authors: Lei Xie, Xin Cui, Chen Shi, Jingyi Wang, Qingxia Liu, Hao Zhang, Qi Liu, Duowei Yuan, Hongbo ZengAbstract:The surface characteristics of molybdenite (MoS2) such as wettability and surface interactions have attracted much research interest in a wide range of engineering applications, such as froth flotation. In this work, a Bubble probe atomic force microscope (AFM) technique was employed to directly measure the interaction forces between an Air Bubble and molybdenite mineral surface before/after polymer (i.e., guar gum) adsorption treatment. The AFM imaging showed that the polymer coverage on the surface of molybdenite could achieve ∼5.6, ∼44.5, and ∼100% after conditioning in 1, 5, and 10 ppm polymer solution, respectively, which coincided with the polymer coverage results based on contact angle measurements. The electrolyte concentration and surface treatment by polymer adsorption were found to significantly affect Bubble–mineral interaction and attachment. The experimental force results on Bubble–molybdenite (without polymer treatment) agreed well with the calculations using a theoretical model based on th...
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Probing Interactions between Air Bubble and Hydrophobic Polymer Surface: Impact of Solution Salinity and Interfacial NanoBubbles
Langmuir : the ACS journal of surfaces and colloids, 2016Co-Authors: Xin Cui, Chen Shi, Lei Xie, Jing Liu, Hongbo ZengAbstract:The interactions between Air Bubbles and hydrophobic polymer surfaces in aqueous media play important roles in many industrial and engineering processes. In this work, the interaction forces between Air Bubble and a model hydrophobic polymer–polystyrene (PS) in NaCl solutions (1 mM to 1000 mM) were directly measured using a Bubble probe atomic force microscope (AFM) technique, and the measured forces were analyzed by a theoretical model based on Reynolds lubrication theory and augmented Young–Laplace equation including the influence of disjoining pressure. It was found that the theoretical analysis, by assuming that the PS surface was a pristine and bare polymer surface in aqueous solutions, could not fully agree with the experimental force measurements at intermedium salinity condition (i.e., 100 mM NaCl), and the discrepancy could not be described by the classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory even including the effects of non-DLVO interactions such as hydrophobic interaction. Atomic fo...
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1 Supporting Information (SI) Measuring Forces and Spatiotemporal Evolution of Thin Water Films between an Air Bubble and Solid Surfaces of Different Hydrophobicity
2016Co-Authors: Chen Shi, Derek Y. C. Chan, Xin Cui, Lei Xie, Hongbo Zeng, Qingxia Liu, Jacob N Israelachvili, Si ExperimentAbstract:AFM force measurement Force measurement between an Air Bubble and a solid surface was conducted using an Asylum MFP-3D Atomic Force Microscopy (AFM) following a previously reported procedure.1-3 The aqueous solution used in the AFM experiments was prepared using sodium chloride (NaCl, Fisher Scientific) with highest purity and Milli-Q water (Millipore deionized) with a specific resistivity greater than 18.2 MΩ·cm. Before force measurement, a custom-made glass pipette with an ultra-sharp end was used to inject Air Bubbles into an AFM fluid cell filled with the aqueous solution to be tested. The glass substrate of the fluid cell was mildly hydrophobized by immersing in 10 mM 2 octadecyltrichlorosilane (OTS, ACROS Organics) solution in toluene for a few seconds that led to a water contact angle of ~50 ° on the glass substrate for Bubble immobilization. An Air Bubble with suitable size (typical radius R0 of 60-100 µm) was picked up with a custom-made rectangular tipless cantilever (400 × 70 × 2 µm) to form an AFM Bubble probe, as shown in Figure S1. The tipless cantilever has a circular patch of gold (diameter 65 µm, thickness 30 nm
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probing the interaction between Air Bubble and sphalerite mineral surface using atomic force microscope
Langmuir, 2015Co-Authors: Lei Xie, Chen Shi, Jingyi Wang, Qingxia Liu, Jun Huang, Hongbo ZengAbstract:The interaction between Air Bubbles and solid surfaces plays important roles in many engineering processes, such as mineral froth flotation. In this work, an atomic force microscope (AFM) Bubble probe technique was employed, for the first time, to directly measure the interaction forces between an Air Bubble and sphalerite mineral surfaces of different hydrophobicity (i.e., sphalerite before/after conditioning treatment) under various hydrodynamic conditions. The direct force measurements demonstrate the critical role of the hydrodynamic force and surface forces in Bubble–mineral interaction and attachment, which agree well with the theoretical calculations based on Reynolds lubrication theory and augmented Young–Laplace equation by including the effect of disjoining pressure. The hydrophobic disjoining pressure was found to be stronger for the Bubble–water–conditioned sphalerite interaction with a larger hydrophobic decay length, which enables the Bubble attachment on conditioned sphalerite at relatively...
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measuring forces and spatiotemporal evolution of thin water films between an Air Bubble and solid surfaces of different hydrophobicity
ACS Nano, 2015Co-Authors: Chen Shi, Derek Y. C. Chan, Xin Cui, Lei Xie, Qingxia Liu, Jacob N Israelachvili, Hongbo ZengAbstract:A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the interaction force and the spatiotemporal evolution of the thin water film between a Bubble in water and mica surfaces with varying degrees of hydrophobicity. Stable films, supported by the repulsive van der Waals–Casimir–Lifshitz force were always observed between Air Bubble and hydrophilic mica surfaces (water contact angle, θw < 5°) whereas Bubble attachment occurred on hydrophobized mica surfaces. A theoretical model, based on the Reynolds lubrication theory and the augmented Young–Laplace equation including the effects of disjoining pressure, provided excellent agreement with experiment results, indicating the essential physics involved in the interaction between Air Bubble and solid surfaces can be elucidated. A hydrophobic interaction free energy per unit area of the form: WH(h) = −γ(1 – cos θw)exp(−h/DH) can be used to quantify the attraction between Bubble an...
Jingming Wang - One of the best experts on this subject based on the ideXlab platform.
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rose petals with a novel and steady Air Bubble pinning effect in aqueous media
Soft Matter, 2012Co-Authors: Jingming Wang, Lei Jiang, Qinglin Yang, Mingchao Wang, Chun WangAbstract:Many well-known natural superhydrophobic surfaces exhibit unique characteristics when immersed in the aqueous medium. In the present paper, the phenomenon of the steady pinning effect of Air Bubbles on a rose petal with a combination of hierarchical rough structures (i.e., micropapillae and nanofolds) is described. The pinning force of a 2 μL Air Bubble is ca. 101.2 μN, and the critical flow velocity of water leading the three-phase contact line (TPCL) to slide is as quick as 124.7 mm s−1. The artificial rose petal surface was prepared from polydimethlsiloxane (PDMS) by a casting technique. It has the same nanofolds and micropapillae as the rose petal surface, and shows a similar Air Bubble pinning effect. The pinning force and the critical flow velocity of the artificial rose petal surface are 140.7 μN and 156.7 mm s−1, respectively. Smooth and rough PDMS films with an ordered nanostructure or patterned microstructure are utilized to study the contribution of the micro/nano hierarchical structures to the Air Bubble pinning effect. Particularly, the facility that the captured Air pockets in the nanostructure of the rose petals (ca. 500–600 nm in width on each micropapilla tip) coalesce with the Air Bubble is shown. The process where a periodic array of microstructures (diameter: 16 μm, height: 7 μm) construct “absorbed” islands to avoid the coalescence between the adjacent Air pockets on the nanofolds is demonstrated as well. The important roles of the size and distribution of the microstructure of the rose petal in the Air Bubble pinning process are highlighted. This steady pinning effect induced on superhydrophobic surfaces with micro/nano hierarchical rough structures should spark further theoretical study on other Bubble-related interfacial phenomena and should open a new avenue for their application in industrial processes, including the cleaning of boats contaminated by plankton and oil, reduction of drag friction on ships and submarine hulls, and the foaming control process.
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Air Bubble bursting effect of lotus leaf.
Langmuir, 2009Co-Authors: Jingming Wang, Jin Zhai, Yongmei Zheng, Lei JiangAbstract:In this paper, a phenomenon of Air Bubbles quickly bursting within several milliseconds on a “self-cleaning” lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar Air Bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of Air Bubble bursting. Air Bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, Air Bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect Air Bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae...
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Air Bubble bursting effect of lotus leaf
Langmuir, 2009Co-Authors: Jingming Wang, Jin Zhai, Yongmei Zheng, Lei Jiang, Fuqiang NieAbstract:In this paper, a phenomenon of Air Bubbles quickly bursting within several milliseconds on a "self-cleaning" lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar Air Bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of Air Bubble bursting. Air Bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, Air Bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect Air Bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae, the width and spacing were significant for Air Bubble bursting. An original model was proposed to further evaluate the reason why the micro/nano hierarchical rough structures had an excellent Air Bubble bursting effect, and the validity of the model was theoretically demonstrated.