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Conference Paper: Electro-hydrodynamic chopping of water-in-water jet in coflowing mcrofluidic channels

TitleElectro-hydrodynamic chopping of water-in-water jet in coflowing mcrofluidic channels
Authors
Issue Date2014
PublisherHong Kong University of Science and Technology.
Citation
Frontiers of Soft Matter Physics: from Non-equilibrium Dynamics to Active Matter, Hong Kong, China, 20-22 January 2014 How to Cite?
AbstractIn the co-flowing capillary microfluidic channels, two immiscible aqueous phases typically forms water-in-water (w/w) jet. Due to the ultra-low interfacial tension (<1mN/m) between the two phases, breakup of the w/w jet can hardly be induced by capillary instability alone [1]. Electrostatic force, applied by separately charging two aqueous phases with different electro-conductivity, can be an auxiliary force to break up the w/w jet. Successful breakup of the w/w jet may provide a new approach for generation of w/w emulsion in an all-aqueous environment free of organic solvents, which are potentially useful in biochemical and biomedical applications. Water-in-water emulsion has been successfully fabricated by hydrodynamic perturbation [1] and electro-hydrodynamic approaches [2]. However, breakup of the w/w jet has not been demonstrated in viscous aqueous phases, which are frequently used in practical solutions. We inject a single phase of sodium dextran sulfate (SDS)/dextran into its immiscible continuous phase of PEG solution to form a w/w jet. Upon applying a DC electric field at 30-80 volts, the viscous jet expands in diameters with the applied voltage [3]. By tracing the velocity of small particles inside the jet, we found the jet velocity is also reduced because of the restriction of mass conservation. When further increasing the applied voltages to 200-1000 volts, we observed an interesting transition from jetting to dripping: along with the deceleration and expansion of the inner fluid, the jet nearly stops in the channel and almost blocks the entire channel before it is chopped and pushed downstream by the continues phase (schematic 1). The jet chopping is induced by force balancing among the electrostatics, hydrodynamics and interfacial tension.
DescriptionJunior Scientist, Postdoc and Student Workshops
Talk #25
Persistent Identifierhttp://hdl.handle.net/10722/201246

 

DC FieldValueLanguage
dc.contributor.authorSong, Yen_US
dc.contributor.authorShum, HCen_US
dc.date.accessioned2014-08-21T07:19:43Z-
dc.date.available2014-08-21T07:19:43Z-
dc.date.issued2014en_US
dc.identifier.citationFrontiers of Soft Matter Physics: from Non-equilibrium Dynamics to Active Matter, Hong Kong, China, 20-22 January 2014en_US
dc.identifier.urihttp://hdl.handle.net/10722/201246-
dc.descriptionJunior Scientist, Postdoc and Student Workshops-
dc.descriptionTalk #25-
dc.description.abstractIn the co-flowing capillary microfluidic channels, two immiscible aqueous phases typically forms water-in-water (w/w) jet. Due to the ultra-low interfacial tension (<1mN/m) between the two phases, breakup of the w/w jet can hardly be induced by capillary instability alone [1]. Electrostatic force, applied by separately charging two aqueous phases with different electro-conductivity, can be an auxiliary force to break up the w/w jet. Successful breakup of the w/w jet may provide a new approach for generation of w/w emulsion in an all-aqueous environment free of organic solvents, which are potentially useful in biochemical and biomedical applications. Water-in-water emulsion has been successfully fabricated by hydrodynamic perturbation [1] and electro-hydrodynamic approaches [2]. However, breakup of the w/w jet has not been demonstrated in viscous aqueous phases, which are frequently used in practical solutions. We inject a single phase of sodium dextran sulfate (SDS)/dextran into its immiscible continuous phase of PEG solution to form a w/w jet. Upon applying a DC electric field at 30-80 volts, the viscous jet expands in diameters with the applied voltage [3]. By tracing the velocity of small particles inside the jet, we found the jet velocity is also reduced because of the restriction of mass conservation. When further increasing the applied voltages to 200-1000 volts, we observed an interesting transition from jetting to dripping: along with the deceleration and expansion of the inner fluid, the jet nearly stops in the channel and almost blocks the entire channel before it is chopped and pushed downstream by the continues phase (schematic 1). The jet chopping is induced by force balancing among the electrostatics, hydrodynamics and interfacial tension.-
dc.languageengen_US
dc.publisherHong Kong University of Science and Technology.en_US
dc.relation.ispartofFrontiers of Soft Matter Physics: from Non-equilibrium Dynamics to Active Matteren_US
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleElectro-hydrodynamic chopping of water-in-water jet in coflowing mcrofluidic channelsen_US
dc.typeConference_Paperen_US
dc.identifier.emailShum, HC: ashum@hku.hken_US
dc.identifier.authorityShum, HC=rp01439en_US
dc.description.naturepublished_or_final_version-
dc.identifier.hkuros233159en_US
dc.publisher.placeHong Kongen_US

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