Mastiani, Mohammad

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.

Aqueous microdroplets have shown great potential
in various applications such as material synthesis,
chemical reactions, and drug discovery. The
objective of this research is to generate aqueous
microdroplets in water using microfluidic techniques.
Compared to conventional aqueous droplets in an oil
phase, droplets generated from the proposed system
will be more biocompatible and simply manufactured.
To achieve this goal, the research focuses on
understanding fundamental physics behind droplet
generation at various geometries and input conditions.
This understanding can subsequently help us
obtain microdroplets with targeted properties. Several
microdroplet generators made of polydimethylsiloxane
(PDMS) transparent polymer are fabricated
and an aqueous two-phase system (ATPS) made up
of two water-based polymers, polyethylene glycol
(PEG) and dextran (DEX) is used in these generators.
The results successfully demonstrate that the
proposed droplet generators produce aqueous microdroplets
at various sizes at different frequencies.
The controllability and tunability of the properties of
microdroplets will be discussed.