AFM characterization of nanobubble formation and slip condition in oxygenated and electrokinetically altered fluids

Bhushan, Bharat; Pan, Yunlu; Daniels, Stephanie L.

doi:10.1016/j.jcis.2012.09.077

Cited by 41 publications

(53 citation statements)

References 51 publications

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“…Saline 1 and saline 2 shows larger and fewer nanobubbles on the PS film compared with DI and saline. Reproduced with permission from [55]. Copyright (2013) Elsevier.…”

Section: Reviewmentioning

confidence: 99%

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The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Pan¹,

Bhushan²,

Zhao³

2014

Beilstein J. Nanotechnol.

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SummaryThe drag of fluid flow at the solid–liquid interface in the micro/nanoscale is an important issue in micro/nanofluidic systems. Drag depends on the surface wetting, nanobubbles, surface charge and boundary slip. Some researchers have focused on the relationship between these interface properties. In this review, the influence of an applied voltage on the surface wettability, nanobubbles, surface charge density and slip length are discussed. The contact angle (CA) and contact angle hysteresis (CAH) of a droplet of deionized (DI) water on a hydrophobic polystyrene (PS) surface were measured with applied direct current (DC) and alternating current (AC) voltages. The nanobubbles in DI water and three kinds of saline solution on a PS surface were imaged when a voltage was applied. The influence of the surface charge density on the nanobubbles was analyzed. Then the slip length and the electrostatic force on the probe were measured on an octadecyltrichlorosilane (OTS) surface with applied voltage. The influence of the surface charge on the boundary slip and drag of fluid flow has been discussed. Finally, the influence of the applied voltage on the surface wetting, nanobubbles, surface charge, boundary slip and the drag of liquid flow are summarized. With a smaller surface charge density which could be achieved by applying a voltage on the surface, larger and fewer nanobubbles, a larger slip length and a smaller drag of liquid flow could be found.

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“…Saline 1 and saline 2 shows larger and fewer nanobubbles on the PS film compared with DI and saline. Reproduced with permission from [55]. Copyright (2013) Elsevier.…”

Section: Reviewmentioning

confidence: 99%

“…The aggregation may lead to the discontinuous increase of the average diameter of nanobubbles in saline 2, which has a small total count of nanobubbles at a voltage of 60 V (Fig. 15) [55]. …”

Section: Reviewmentioning

confidence: 99%

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Pan¹,

Bhushan²,

Zhao³

2014

Beilstein J. Nanotechnol.

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View full text Add to dashboard Cite

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“…Following the suggestion by Parker et al in 1994 [1] on the presence of stable nanobubbles on a hydrophobic surface, they have been directly observed with scanning atomic force microscopy (AFM) since 2000 [2][3][4][5][6][7][8][9][10]. Nanobubbles are usually formed by the exchange of a short-chain alcohol with water on a solid substrate called the standard solvent exchange procedure [6,11,12].…”

Section: Introductionmentioning

confidence: 99%

Advanced dynamic-equilibrium model for a nanobubble and a micropancake on a hydrophobic or hydrophilic surface

et al. 2015

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The dynamic-equilibrium model for stabilization of a nanobubble on a hydrophobic surface by Brenner and Lohse [M. P. Brenner and D. Lohse, Phys. Rev. Lett. 101, 214505 (2008)] has been modified taking into account the van der Waals attractive force between gas molecules inside a nanobubble and solid surface. The present model is also applicable to a nanobubble on a hydrophilic surface. According to the model, the pressure inside a nanobubble is not spatially uniform and is relatively higher near the solid surface. As a result, there is gas outflux near a hydrophilic surface, while near a hydrophobic surface there is gas influx which has been already suggested. In the present model, the radius of curvature for a nanobubble depends on the distance from the solid surface because the pressure depends on it. The shape of the micropancake, which is a nearly-two-dimensional bubble, is reproduced by the present model due to the strong dependence of the radius of curvature on the distance from the solid surface. The effect of temperature on the stability of a nanobubble or micropancake is also discussed.

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“…The detailed process to prepare RNS60 is described in our previous work. 49 The process to prepare the PS sample was the same as our previous method 11 and is as follows. First, a 1 cm × 1 cm substrate of Si wafer (Silicon Quest International) with 300 nm thick silicon oxide coating was first immersed in a piranha solution of a 3:1 (volume ratio) mixture of 98% sulfuric acid and 30% hydrogen peroxide for 30 min, and then rinsed by DI water followed by ethanol at least five times and dried with clean compressed air.…”

Section: Methodsmentioning

confidence: 99%

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles

Jing

Pan

et al. 2016

Langmuir

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The contact angle (CA) of surface nanobubbles is believed to affect the stability of nanobubbles and fluid drag in micro/nanofluidic systems. The CA of nanobubbles is dependent on size and is believed to be affected by the surface charge-induced electrical double layer (EDL). However, neither of these of attributes are well understood. In this paper, by introducing an EDL-induced electrostatic wetting tension, a theoretical model is first established to study the effect of EDLs formed near the solid-liquid interface and the liquid-nanobubble interface on the gas phase CA of nanobubbles. The size-dependence of this EDL interaction is studied as well. Next, by using atomic force microscopy (AFM), the effect of the EDL on nanobubbles' gas phase CA is studied with variable electrical potential at the solid-liquid interface, which is adjusted by an applied voltage. Both the theoretical and the experimental results show that the EDLs formed near the solid-liquid interface and the liquid-nanobubble interface lead to a reduction of gas phase CA of the surface nanobubbles because of an electrostatic wetting tension on the nanobubble due to the attractive electrostatic interaction between the liquid and nanobubble within the EDL, which is in the nanobubbles' outward direction. An EDL with a larger zeta potential magnitude leads to a larger gas phase CA reduction. Furthermore, the effect of EDL on the nanobubbles' gas phase CA shows a significant size-dependence considering the size dependence of the electrostatic wetting tension. The gas phase CA reduction due to the EDL decreases with increasing nanobubble height and increases with the nanobubble's increasing curvature radius, indicating that a surface charge-induced EDL could possibly explain the size dependence of the gas phase CA of nanobubbles.

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AFM characterization of nanobubble formation and slip condition in oxygenated and electrokinetically altered fluids

Cited by 41 publications

References 51 publications

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

Advanced dynamic-equilibrium model for a nanobubble and a micropancake on a hydrophobic or hydrophilic surface

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles

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