Droplet Microfluidics

1. Aqueous-Two Phase System Droplet Generation

Recent advent of Aqueous-Two-Phase-System (ATPS), more biologically friendly compared to conventional oil-water systems, has shown great potential to rapidly generate aqueous droplets without tedious post-processing. However, understanding of the underlying physics of droplet formation in ATPS is still in its infancy. We are aiming to generate aqueous droplets in the aqueous phase at high frequency of generation with much smaller size when compared with the conventional methods.



2. High Inertial Droplet Microfluidics

Droplet-based microfluidics have become ubiquitous and of great importance for applications in biological and chemical fields including drug delivery.  Unlike typical oil-liquid systems, we are here aiming at using gas-liquid scheme to make it possible to create digital droplet microfluidics systems in applications that require high inertial effects due to the presence of a gaseous phase.  There are two main research thrusts in droplet microfluidics research:


1) Droplet generation at T-junction or flow focusing geometries

Using various microchannel geometries, several aspects of high inertial droplet flows such as geometry dependence, flow regime mapping, and interactions of forces (surface tension, viscous force, inertial forces, etc.) will be investigated.


<Experimental Setup>


<Droplet Generation: dripping>


<Droplet Generation: jetting>


2) High inertial droplet mixing by chaotic advection

High inertial droplet flows will also be employed to enhance micromixing by chaotic advection at high Reynolds number flows, compared to conventional oil-liquid systems.


<Schematic of Collision Droplet Mixing*>


<Sequential Fluorescence Images of Droplet Collision*>

* Reference: B. Carroll, C. Hidrovo, Exp Fluid, 2012

3. Polymeric Bio-Particle Synthesis

One of significant hindrances in sustained pulmonary drug delivery is low efficiency of drug absorption.  The major reason in this poor inhalation uptake is the fact that the drug size is too large to inhale.  The most appropriate aerodynamic size range for particles to be respirable is 0.5-5 um. The strategy for sustained controlled pulmonary drug delivery involves the engineering of dried delivery carrier systems that are able to provide respirable aerodynamic size, and offer stealth characteristics to hide themselves from macrophages in addition to showing desirable controlled releases kinetics.  This research will develop methodologies to make polymeric biodegradable particles at a scale of target aero diameter as a drug carrier system using microfluidics techniques.

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<Polymerization of calcium alginate in a bulk phase>


<Generation of droplet family>