The microenvironment of double emulsions in rectangular microchannels

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Title: The microenvironment of double emulsions in rectangular microchannels
Authors: Ma, S
Sherwood, JM
Huck, WTS
Balabani, S
Item Type: Journal Article
Abstract: The flow environment in inner cores of water-in-oil-in-water (w/o/w) microfluidic double emulsions has a significant impact on industrial applications of such systems. For example, in the case of shear sensitive cells compartmentalised in the cores, high shear conditions may be deleterious. This study reports on the flow characteristics of w/o/w inner cores in comparison to those in single water-in-oil (w/o) microdroplets of equal size moving in the same microchannel, resolved by means of micro-particle image velocimetry (μPIV). The multiphase flow system employed in the study had a viscosity ratio, λ, between aqueous and oil phase of the order of unity (λ = 0.78) and both single droplets and inner cores of double emulsions filled the channel. This configuration resulted in a weak recirculating flow inside the w/o single droplet: the measured flow field exhibited a uniform low velocity flow field in the central region surrounded by small regions of reversed flow near the channel walls. This flow topology was maintained in the inner cores of w/o/w double emulsions for intermediate capillary numbers (Ca) ranging from 10−3 to 10−2, and core morphologies varying from large plugs to pancake cores. The core morphology affected the magnitude and distribution of the velocity in the droplets. The similarity in the flow topology resulted from the fact that inner cores were located at the back of the outer droplet in such a way that inner and outer interfaces were in contact for over half of core surface area and separated only by a thin lubricating film. Both single droplets and inner cores exhibited a narrow shear rate distribution characterised by small regions of maximum shear confined near the channel walls. Shear rate magnitude values were found to be an order of magnitude lower than those in the channel and hence capable of reducing stresses in flow cytometry to far below reported values for cell damage. Hence, it can be concluded that double emulsions are suitable candidates to substitute single droplets in flow cytometry to protect the screened items and are compatible with the commercial flow cytometry systems.
Issue Date: 16-Apr-2015
Date of Acceptance: 14-Apr-2015
ISSN: 1473-0197
Publisher: Royal Society of Chemistry
Start Page: 2327
End Page: 2334
Journal / Book Title: Lab on a Chip
Volume: 15
Issue: 10
Copyright Statement: © 2015 Royal Society of Chemistry
Keywords: Science & Technology
Life Sciences & Biomedicine
Physical Sciences
Biochemical Research Methods
Chemistry, Multidisciplinary
Nanoscience & Nanotechnology
Biochemistry & Molecular Biology
Science & Technology - Other Topics
Lab-On-A-Chip Devices
Models, Theoretical
Analytical Chemistry
03 Chemical Sciences
09 Engineering
Publication Status: Published
Appears in Collections:Bioengineering

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