Microbubbling by co-axial electrohydrodynamic atomization

Farook, U.; Stride, Eleanor; Edirisinghe, Mohan; Moaleji, R.

doi:10.1007/s11517-007-0210-1

Cited by 78 publications

(76 citation statements)

References 36 publications

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“…The reduction in bubble size with the reduction in the gas flow rate at a constant lipid suspension flow rate indicated in table 2 agrees with the previous observations in microbubbling by both microfluidic techniques and CEHDA for other liquids (Ganan-Calvo 2004;Garstecki et al 2005;Farook et al 2007b).…”

Section: Resultssupporting

confidence: 90%

“…The bubble dripping, coning and microbubbling modes observed during CEHDA of the air-lipid system are shown in figure 2a-c, respectively. The evolution of these modes is discussed in detail in Farook et al (2007b). With the increase in the applied voltage and hence the increase in the magnitude of the electric field, the bubble dripping mode transforms to the microbubbling mode via the coning mode.…”

Section: Resultsmentioning

confidence: 99%

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Preparation of suspensions of phospholipid-coated microbubbles by coaxial electrohydrodynamic atomization

Farook

Stride

Edirisinghe

2008

J. R. Soc. Interface.

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The use of phospholipid-coated microbubbles for medical applications is gaining considerable attention. However, the preparation of lipid-coated microbubble suspensions containing the ideal size and size distribution of bubbles still represents a considerable challenge. The most commonly used preparation methods of sonication and mechanical agitation result in the generation of polydisperse microbubbles with diameters ranging from less than 1 mm to greater than 50 mm. Efforts have been made via distinctly different techniques such as microfluidic and electrohydrodynamic bubbling to prepare lipid-coated microbubbles with diameters less than 10 mm and with a narrow size distribution, and recent results have been highly promising. In this paper, we describe a detailed investigation of the latter method that essentially combines liquid and air flow, and an applied electric field to generate microbubbles. A parametric plot was constructed between the air flow rate (Q g ) and the lipid suspension flow rate (Q l ) to identify suitable flow rate regimes for the preparation of phospholipid-coated microbubbles with a mean diameter of 6.6 mm and a standard deviation of 2.5 mm. The parametric plot has also helped in developing a scaling equation between the bubble diameter and the ratio Q g /Q l . At ambient temperature (228C), these bubbles were very stable with their size remaining almost unchanged for 160 min. The influence of higher temperatures such as the human body temperature (378C) on the size and stability of the microbubbles was also explored. It was found that the mean bubble diameter fell rapidly to begin with but then stabilized at 1-2 mm after 20 min.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Preparation of suspensions of phospholipid-coated microbubbles by coaxial electrohydrodynamic atomization

Farook

Stride

Edirisinghe

2008

J. R. Soc. Interface.

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“…Recent work (Farook et al 2007a,b, 2009a,b,c, Ahmad et al 2008, Pancholi et al 2008a,b, Stride et al 2008) has helped to develop new methods for preparing bubble suspensions based on electrohydrodynamic processing and microfluidics. The former can generate 10 9 bubbles min -1 from a single nozzle and has been shown to produce coated bubbles in the 1 to 10 µm diameter range with a high degree of predictability and control over size, size distribution and coating characteristics.…”

Section: Foamingmentioning

confidence: 99%

“…This arrangement could provide a more persistent foam if it was combined with local enhancement of nutrients to encourage the growth of marine organisms that excrete surfactants and viscosity modifiers to enhance the stability of foam. This may be one of the best methods to obtain long-term ocean albedo management, but of course, foam stabilisation would reduce the impact on marine cloud by reducing the production rate of CCN.Recent work (Farook et al 2007a,b, 2009a,b,c, Ahmad et al 2008, Pancholi et al 2008a,b, Stride et al 2008) has helped to develop new methods for preparing bubble suspensions based on electrohydrodynamic processing and microfluidics. The former can generate 10 9 bubbles min -1 from a single nozzle and has been shown to produce coated bubbles in the 1 to 10 µm diameter range with a high degree of predictability and control over size, size distribution and coating characteristics.…”

mentioning

confidence: 99%

Can oceanic foams limit global warming?

Evans

Stride²,

Edirisinghe³

et al. 2010

Clim. Res.

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When the diverse methods proposed for solar radiation management are surveyed, a relatively simple, environmentally acceptable, double-acting mechanism for increasing the earth's albedo emerges. It is a low-level environmental intervention that enhances a mechanism already active in nature by increasing the foam fraction of the ocean surface. Bubble rafts increase the optical reflectivity of the ocean and when bubbles burst, they launch seasalt particles that loft and increase the number concentration of cloud droplets in the marine boundary layer, thus increasing the reflectivity of stratocumulus. A strategy based on recent research for producing microbubbles appears to be the best option for large-scale use. KEY WORDS: Ocean albedo · Foam · Bubble generation · Cloud brighteningResale or republication not permitted without written consent of the publisher Clim Res 42: 155-160, 2010 was a proposal to float buoyant reflective particles on the sea (Keith 2000). Others have modelled the effects of changing the albedo of human settlement and grassland (Hamwey 2007).One of the softest albedo interventions is prompted by the work of Twomey (1971) on the relation between droplet size, concentration and reflectivity of clouds. Latham et al. (2008) proposed a method of climate forcing that involves spraying fine droplets of seawater into the troposphere. This has been developed into an engineering proposal by Salter et al. (2008). It is a forgiving strategy; if unwanted effects arise, seasalt is rained out in about 0.5 Ms, whereas additions to the stratosphere may reside for 120 Ms, to be augmented by unpredictable levels of volcanic particle injection. There are no issues of military abuse that may attend the deployment of space parasols. Nor is there danger to air traffic corridors resulting from metallised balloons or mineral powder losing height. In order to combat a 5°C global temperature rise it would be necessary to lift up to 30 Mg s -1 seawater in addition to the 300 Mg s -1 lofted by the oceans (Jaenicke 1993). The spray technology proposed by Latham et al. (2008) and Salter et al. (2008) involves a large number of sizable sea-going, windpowered vessels in which filtered seawater is pumped through sub-micron holes etched in silicon wafers. The aim is not to nucleate new cloud but to increase the number concentration of droplets in existing cloud regions so that reflectivity to incoming shortwave radiation is increased. A narrow droplet size distribution is needed to inhibit Ostwald ripening of droplets and to preserve the stability of cloud cover against rain-out. The challenge is to prevent droplet coagulation and hence coarsening of the sprayed droplet distribution in the plume, for which electrostatic charging of droplets is proposed. FOAMINGWith this in mind, the double-acting intervention of creating oceanic foam to increase ocean surface albedo and coincidently increase the albedo of marine stratocumulus cloud appears to have advantages. It builds on existing natural processes and is simplist...

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“…One of these is on a model for deep tissue injury during prolonged wheelchair sitting [4] on which an expert reviewer commented: 'This is a good attempt to understand the contributions of many biomechanical factors for the risk for injury in the gluteus muscle pad during prolonged sitting'. Another example of such a jewel is an experimental study on the production of suspensions of microbubbles with a controlled diameter and tight size distribution, which is highly relevant for applications in ultrasound diagnosis and drug delivery [3]. This paper stimulated plans for a special issue on the production and use of microbubbles that is slated to appear in the spring of 2009.…”

mentioning

confidence: 99%

The Nightingale Prize 2007

Spaan

2008

Med Biol Eng Comput

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Microbubbling by co-axial electrohydrodynamic atomization

Cited by 78 publications

References 36 publications

Preparation of suspensions of phospholipid-coated microbubbles by coaxial electrohydrodynamic atomization

Preparation of suspensions of phospholipid-coated microbubbles by coaxial electrohydrodynamic atomization

Can oceanic foams limit global warming?

The Nightingale Prize 2007

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