Droplet-based microfluidics.

Abstract

In this thesis, the background of both microfluidics and droplet-based microfluidics are first introduced and presented. Next, the objectives and scopes are defined to give a clear understanding on the research topic. The literature of droplet formation in different configurations is then reviewed thoroughly through many different past works. Basic characteristics of the nature of ferrofluids and applications are also reviewed.

Firstly, the temperature dependence of droplet formation in a flow focusing microfluidic device is investigated. Both DI water and nanofluids were used to generate droplets at different temperature. The heat generated by the integrated micro heater changes the droplet formation process and increases the size of the droplet due to the dominance of viscosity over interfacial tension. At constant flow rates, three different droplet formation regimes were observed in both fluids. Experimental results also demonstrated that water-based nanofluid exhibits similar characteristics as DI water. Furthermore, a change in the nanofluid flow rates has little effect on the size of the droplet formed.