Characterizing optically trapped double emulsion droplets for water treatment
Begeleider(s): ir. Stijn Vandewiele en ir. Mathieu Balcaen


This thesis is part of a collaboration between the Liquid Crystal and Photonics Group and the Particle and Interfacial Technology Group. One of the research areas of PaInT is water treatment.
Eliminating organic micro polluents from water is a laborious task. A novel way to accomplish this is the use of double emulsions (water-in-oil-in-water particles). They serve as a membrane to perform the encapsulation of micro polluents.

Exchange of organic compounds through the oil barrier is greatly determined by their ionisation state. By having a different pH in the interior water phase the compounds dissociate in the internal water droplets. Hereby a one-direction transport from the outer phase to the inner phase is attainable. This allows us to extract the present micro polluents from the environment in an easy way.

Optical tweezers allow to exert forces on microscopical objects. They will be used to immobilize individual double emulsion droplets so they can be studied during a long time, allowing us to characterize the extraction of micro polluents.  


Example of fluorescently labelled double emulsions (W. Wang et. al., Lab Chip, 2011,11, 1587-1592), and a double emulsion droplet in an optical trap.



In this thesis fluorescent dyes dissociating at a certain pH level will serve as a model molecule for the micro polluents. Part of this thesis will be to test different dyes and choose the best dyes for the job.

In the LCP group, we have built a versatile state-of-the-art optical trapping setup. To measure the dynamics and efficiency of the exchange, a single double emulsion droplet will be trapped with our optical tweezer setup allowing measurements for an extensive period of time. Associated problems to be tackled are the drop size determination of the droplets and the design of a microfluidic cell suitable for optical trapping and particle environment control.

The staff of the LCP group and the PaInT group will provide you with all the necessary help and know-how, but we also encourage you to take the initiative to come up with your own ideas to tackle the project. Where feasible and within the scope of the project, we'll support you to develop these ideas.

Fabrication of the double emulsions will be done at the PaInT group, Coupure Links 653.
Fabrication of the microfluidic chip is done in the cleanroom, Zwijnaarde.
Measurements with the optical trap/fluorescence microscope are done at the Liquid Crystal & Photonics group, Technicum.