Novel swirl flow-focusing microfluidic device for the production of monodisperse microbubbles
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A novel swirl flow-focusing microfluidic axisymmetric device for the generation of monodisperse microbubbles at high production rates to be used as in-line contrast agents for medical applications is presented. The swirl effect is induced upstream of the discharge orifice by a circular array of microblades which form a given angle with the radial direction. The induced vortical component on the focusing liquid stabilizes the gas meniscus by the vorticity amplification due to vortex stretching as the liquid is forced through the discharge orifice. The stabilized meniscus tapers into a steady gas ligament that breaks into monodisperse microbubbles. A reduction up to \(57\%\) in the microbubble diameter is accomplished when compared to conventional axisymmetric flow-focusing microdevices. An exhaustive experimental study is performed for various blade angles and numerous gas to liquid flow rate ratios, validating previous VoF numerical simulations. The microbubbles issued from the stabilized menisci verify prior scaling law of flow-focusing.
KeywordsMicrobubble Flow-focusing Swirl
The authors would like to acknowledge financial support from Spanish Government Ministry MEIC and Regional Government under the Contract DPI2013-46485 and P11-TEP-7465, respectively. They would also like to acknowledge the technical assistance of S. Schlautmann in the fabrication of the microfluidic devices and Manuel González and Jorge López for their technical assistance during the setup preparation.
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