PhD Oral Qualifying Examination : Fundamentals and applications of light confinement in microfluidic emulsions

Speaker Zheng Lu (Supervisors: A/Prof Saif Khan)

Host Department of Chemical and Biomolecular Engineering

Date/Time 20 Sep - 20 Sep, 10.00AM

Venue E5-03-21 , Faculty of Engineering, National University of Singapore


Microfluidic emulsions are droplets of one liquid (fl to nl volumes) suspended in another immiscible liquid within a microchannel. Besides enhanced mass and heat transport properties intrinsic to microfluidics, compartmentalization of droplet contents and high droplet generation frequencies (upto kHz) enable several novel high-throughput screening applications. Furthermore, due to their small sizes and surfaced tension smoothened spherical surfaces, microfluidic emulsions allow highly efficient light confinement at their surfaces, in effect acting as cavities (‘resonators’) that can trap light. There has been considerable interest in recent years in such optofluidic systems and droplet-based light confinement has been studied with a strong focus on optical sensing applications. In this seminar, I will demonstrate the use of droplets as miniaturized reaction flasks in which, by exploiting novel modes of light confinement in microfluidic emulsions, it is possible to embed fluidic laser light sources within or around the reaction flasks. With the embedded laser sources, each microfluidic droplet now functions not only as an isolated experiment flask, but is also capable of on drop sensing, thus expanding the possibilities for online monitoring of biophysical/biochemical processes and sensitive detection of biomolecules. Furthermore, I will discuss ideas for future work focusing on accelerated photochemistry in droplets with embedded laser light sources that could potentially revolutionize the way photochemical transformations are conducted.