Electrowetting-enhanced microfluidic device for drop generation

Gu, Huanghe; Malloggi, Florent; Vanapalli, Siva A.; Mugele, Friedrich Gunther

doi:10.1063/1.3013567

Cited by 52 publications

(46 citation statements)

References 21 publications

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“…In accord with Goren's analysis, the droplet break up appears to be weakly dependent on Ohnesorge number (Table 1). Similar behavior has been observed in studies of electrowetting in microfluidic devices [45]. …”

Section: Droplet Break-up In the Absence Of An Electric Fieldsupporting

confidence: 63%

Free surface electrospinning from a wire electrode

Forward

Rutledge

2012

Chemical Engineering Journal

145

110

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Electrostatic jetting from a free liquid surface offers an alternative to conventional electrospinning in which jets are emitted from spinnerets. In this work we analyze a system in which a wire electrode is swept (in a rotary motion) through a bath containing a polymeric solution in contact with a high voltage, resulting in entrainment of the fluid, the formation of liquid droplets on the wire and electrostatic jetting from each liquid droplet. Solutions of polyvinylpyrrolidone in ethanol were used as test systems to evaluate each stage of the process.The volume of individual droplets on the wire were measured by photographic methods and correlated with the viscosity, density and surface tension of the liquid, and with system parameters such as electrode rotation rate and wire diameter. The local electric field in the absence of liquid entrainment was modeled using conventional electrostatics, and jet initiation was found to occur consistently at the angular position where the electric field exceeds a critical value of 34 kV/cm, regardless of rotation rate. Two operating regimes were identified. The first is an entrainment-limited regime, in which all of the entrained liquid is jetted from the wire electrode. The second regime is field-limited, in which the residence time of the wire electrode in an electric field in excess of the critical value is too short to deplete the fluid on the wire. The productivity of the system was measured and compared to the theoretical values of liquid entrainment. As expected, highest productivity occurred at high applied potentials and high rotation rates.

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Section: Droplet Break-up In the Absence Of An Electric Fieldsupporting

confidence: 63%

Free surface electrospinning from a wire electrode

Forward

Rutledge

2012

Chemical Engineering Journal

145

110

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“…The active techniques encompass the use of electric, magnetic, or centrifugal fields, just to name a few. External forces are not only used to generate droplets (Gu et al, 2008;Gañán-Calvo et al, 2006), but also to manipulate them downstream as, for example, droplet coalescence, splitting and mixing (Ray et al, 2017;Budden et al, 2013;Chokkalingam et al, 2014). Droplet cluster formation has been achieved using passive methods with a potential to serve as building blocks for new materials (Shen et al, 2016).…”

mentioning

confidence: 99%

Droplet group production in an AC electro-flow-focusing microdevice

Castro-Hernández

García-Sánchez

Velencoso-Gómez

et al. 2017

Microfluid Nanofluid

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We report the production of droplet groups with a controlled number of drops in a microfluidic electro-flow focusing device under the action of an AC electric field. This regime appears for moderate voltages (500-700 V peak-to-peak) and signal frequencies between 25 and 100 Hz, much smaller than the droplet production rate (∼ 500 Hz). For this experimental conditions the production frequency of a droplet package is twice the signal frequency. Since the continuous phase flow in the microchannel is a Hagen-Poiseuille flow, the smaller droplets of a group move faster than the bigger ones leading to droplet clustering downstream.

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“…For example, Gu used this technique in a flow-focusing device to control droplet formation in the channel. 18 Here, we design a device that combines the electrowetting technique and step-emulsification to demonstrate the basic principle of electrowetting step-emulsification. After fabricating the device and carrying out the experiments, the figure of relationship among droplet size, flow rate and voltage applied is obtained.…”

Section: All Article Content Except Where Otherwise Noted Is Licensmentioning

confidence: 99%

Creating monodispersed droplets with electrowetting-on-dielectric step emulsification

Huang

et al. 2018

AIP Advances

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Monodisperse droplets are important in drug screening, and cell-based and biochemical research. However, conventional methods for creating droplets, such as co-flow, T-junction and flow-focusing, have poor monodispersity because of fluctuations in the flow rate. Because step emulsification is based on the principle of Laplace pressure, it is insensitive to the flow rate and yields a constant and high monodispersity. In the present study, we combine electrowetting and step emulsification to reduce the negative influence of flow-rate fluctuations and to prepare highly monodisperse droplets. We demonstrate that the flow rate and voltage applied to the droplets can independently influence the droplet size. This method has great potential in chip-based bioanalysis and cell-based studies where highly monodisperse droplets are needed.

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Electrowetting-enhanced microfluidic device for drop generation

Cited by 52 publications

References 21 publications

Free surface electrospinning from a wire electrode

Free surface electrospinning from a wire electrode

Droplet group production in an AC electro-flow-focusing microdevice

Creating monodispersed droplets with electrowetting-on-dielectric step emulsification

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