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" Aqueous Microdroplet Generation in Oil-free Environments "
Mastiani, Mohammad
Kim, Myeongsub M
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Latin Dissertation
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English
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| Record Number
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1052314
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| Doc. No
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TL51431
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| Main Entry
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Mastiani, Mohammad
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| Title & Author
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Aqueous Microdroplet Generation in Oil-free Environments\ Mastiani, MohammadKim, Myeongsub M
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| College
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Florida Atlantic University
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| Date
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2019
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| Degree
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Ph.D.
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2019
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| Note
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149 p.
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| Abstract
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Droplet microfluidics generates and manipulates microdroplets in microfluidic devices at high manufacturing efficiency and controllability. Microdroplets have proven effective in biomedical applications such as single-cell analysis, DNA sequencing, protein partitioning and drug delivery. Conventionally, a series of aqueous microdroplets containing biosamples is generated and controlled in an oil environment. One of the critical challenges in this system is that recovery of the aqueous samples from the oil phase is very difficult and often requires expensive and cumbersome post-processing. Also, the low Reynolds (Re) number characteristic of this system results in low throughput of droplet generation. To circumvent challenges and fully utilize microdroplets for practical clinical applications, this research aims to unpack the fundamental physics that governs droplet generation in oil-free systems including an aqueous two-phase system (ATPS) and a high inertial liquid-gas system. We experimentally and numerically studied the droplet morphology, droplet breakup mechanisms, droplet generation frequency, monodispersity and different flow regimes of droplet generation in ATPS and high inertial water-in-air (W/A) system. We passively produced ATPS droplets with a wide range of droplet size and high production rate (~ 300 Hz) without the involvement of an oil phase and external forces. For the first time, we reported important information of the flow rate and Capillary (Ca) number for passive, oil-free ATPS droplet generation. In addition, passive generation of salt-based ATPS microdroplets for cell encapsulation and their biocompatibility test were studied. On the other hand, aqueous microdroplet generation in the W/A system in microfluidic flow-focusing and T-junction geometries was studied numerically. At various Re and Ca numbers, several flow regimes were identified including squeezing, dripping, unstable dripping, plugging, stratified flow, multi-satellite droplet formation, and unstable jetting. Unstable dripping, multi-satellite droplet formation, and unstable jetting have been observed as new flow regimes in our study which have not been previously reported. The maximum generation frequency of ~ 2K Hz was obtained under the unstable dripping regime in the flow-focusing geometry. It was found that increasing Re number results in droplet size reduction, while higher Ca number leads to bigger droplets.
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| Descriptor
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Mechanical engineering
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Kim, Myeongsub M
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Florida Atlantic University
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