Experimental and numerical study of temperature-actuated droplets within microfluidics

Droplet microfluidics (DM), which involves the production of nano-/micro- droplets and particles using immiscible phases, reveals an impressive evolutionary trend that have been widely used to establish highly sensitive, robust, and flexible multitasking microsystems. Droplets generated by DM systems can operate thousands of parallel reactions without increasing device size or complexity which facilities the possibility of developing miniaturized fully integrated high‐throughput screening devices. The high surface-to-volume ratio offered by micro-drops ensures the rapid heat and mass transfer and makes thermal stimulation a powerful actuation technique to perform exquisite transporting, mixing, melting, and changing the volume formed droplets. The work aims to numerically and experimentally analyze the droplet generation and behavior when heat is applied to a flow-focusing microstructure under variable flow conditions. The study focused on two main topics; (1) Studying the effect of temperature variation on the behavior water droplets emulsified in mineral oil when heat is applied to the downstream channel. (2) Examining at 37C the size and generation regimes of agarose droplet dispersed in mineral oil. The study had several parts: designing and manufacturing a microchannel network to allow experimental investigation of the characteristics of the droplets, heater calibration and location determination to best fit the selected applications, and applying numerical simulations to understand the hydrodynamics and physics controlling the droplets. Results obtained from temperature alteration of water-in-oil micro-dispersions indicate that the temperature has a dominant effect on the size and the local stability of the droplets in the micro-channels. While, the results observed from exploring the formation of agar-in-oil emulsion demonstrate the significance of capillary number Ca and fluids flow rate ratios �� on the droplet size and the transformation from squeezing into dripping or jetting regimes. The findings of this work assist the future works of performance optimization of on-chip DNA amplification devices and encapsulating bacteria and live cells in agarose droplets for drug delivery applications.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Engineering – Mechanical & Manufacturing

Grantor dc:publisher.institution

Schulich School of Engineering

Year dc:date.issued

2019

Author dc:creator

• Ali Khater, Asmaa Ali ElAwadi

Advisors dc:contributor.advisor

• Mohamad, Abdulmajeed Abd
• Sanati-Nezhad, Amir

Committee members dc:contributor.committeemember

• Ren, Carolyn L.
• Azaiez, Jalel
• Johansen, Craig T.
• Benneker, Anne M.

• Droplet generation - Water-in-oil emulsion - Agar-in-oil emulsion - Heat transfer - Non-Newtonian fluids - Agarose droplets - Multi-phase flow - Droplet manipulation - Flow-focusing -

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/36445

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/110262