On the corona discharge spreading of dielectric liquid films

Mahmoudi, Seyed Reza; Adamiak, K.; Castle, G.S.P.

doi:10.1016/j.elstat.2012.12.038

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…Controlled spreading of droplets and liquid films over a solid substrate has widespread use in applications such as coating, printing, micro- and bio-fluidics to name a few. Recently, it has been proposed that corona discharge can be an effective technique for controlled droplet spreading [ 1 , 2 ]. Corona discharge is effected by the ionization of air in the vicinity of a sharp-tipped conductor carrying a high voltage.…”

Section: Introductionmentioning

confidence: 99%

The Electric Honeycomb; an investigation of the Rose window instability

Niazi¹

2017

R. Soc. open sci.

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The Rose window instability is a little-explored electrohydrodynamic instability that manifests when a layer of low-conducting oil is placed in an electric field generated by corona discharge in a point-to-plane configuration. Above a critical voltage, the instability starts as a single dimple in the oil layer right below the point electrode and subsequently evolves into a characteristic pattern of polygonal cells. In this study, we experimentally explore governing parameters that guide the instability and document geometric attributes of the characteristic cellular pattern. The driving force for the instability has been attributed to the buildup of charged ions which in turn apply an electric pressure on the oil surface. We confirm the charged surface distribution using thermal imaging and demonstrate that the instability can be locally inhibited by preventing charge buildup under an ion shadow.

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Section: Introductionmentioning

confidence: 99%

The Electric Honeycomb; an investigation of the Rose window instability

Niazi¹

2017

R. Soc. open sci.

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“…Electric fields can be used for droplet manipulation on horizontal substrates, − controlling contact-angle hysteresis on inclined planes, and deforming drops containing colloidal particles. , The effects of electric fields on gravity-driven flow of thin films over topography in the absence of contact lines have also been studied for perfectly conducting liquids and perfect dielectric liquids . All of these configurations are relevant to microfluidics .…”

Section: Introductionmentioning

confidence: 99%

Spreading of Thin Droplets of Perfect and Leaky Dielectric Liquids on Inclined Surfaces

Corbett

Kumar

2016

Langmuir

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The spreading of droplets may be influenced by electric fields, a situation that is relevant to applications such as coating, printing, and microfluidics. In this work we study the effects of an electric field on the gravity-driven spreading of two-dimensional droplets down an inclined plane. We consider both perfect and leaky dielectric liquids, as well as perfectly and partially wetting systems. In addition to the effects of electric fields, we examine the use of thermocapillary forces to suppress the growth of the capillary ridge near the droplet front. Lubrication theory is applied to generate a set of coupled partial differential equations for interfacial height and charge, which are then solved numerically with a finite-difference method. Electric fields increase the height of the capillary ridge in both perfect and leaky dielectric droplets due to electrostatic pressure gradients that drive liquid into the ridge. In leaky dielectrics, large interfacial charge gradients in the contact-line region create shear stresses that also enhance ridge growth and the formation of trailing minor ridges. The coalescence of these ridges can significantly affect the long-time thinning rate of leaky dielectric droplets. In partially wetting liquids, electric fields promote the splitting of smaller droplets from the primary droplet near the receding contact line due to the interplay between electrostatic forces and disjoining pressure. Cooling from below and heating from above generates thermocapillary forces that counteract the effects of electric fields and suppress the growth of the capillary ridge. The results of this work have important implications for manipulating the spreading of droplets down inclined surfaces.

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Optical performance enhancement of chip-on-board light-emitting diodes through ionic wind patterning

Chu

Zhang

et al. 2017

Appl. Opt.

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Due to the total internal reflection at the upper interface of the encapsulation layer, the light extraction efficiency (LEE) of chip-on-board packaging light-emitting diodes is attenuated significantly. It is well known that the LEE can be enhanced by patterning the encapsulation layer. In this study, a novel method of patterning the encapsulation layer, which is based on the interaction between the ionic wind and liquid encapsulation, is proposed and demonstrated. Two kinds of encapsulation patterns, namely dual stripe and meniscus, were fabricated successfully. Compared with the traditional flat encapsulation structure, dual stripe and meniscus patterns enhanced the LEE by 17.78% and 20.48%, respectively. Meanwhile, light intensity distributions were observed to be more uniform. The proposed encapsulation patterning method demonstrates significantly simplified fabrication process and reduced cost.

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On the corona discharge spreading of dielectric liquid films

Cited by 3 publications

References 11 publications

The Electric Honeycomb; an investigation of the Rose window instability

The Electric Honeycomb; an investigation of the Rose window instability

Spreading of Thin Droplets of Perfect and Leaky Dielectric Liquids on Inclined Surfaces

Optical performance enhancement of chip-on-board light-emitting diodes through ionic wind patterning

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