Droplet deformation in microfluidic extensional flow

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Surface modifiers at the liquid-liquid interface are of great interest to create stabilized emulsions and to modify the behavior of droplets. These droplets with surface modifiers have numerous applications, like drug delivery, material development, and cosmetics. There has been great interest in the behavior and material properties of the droplets. Especially during manufacturing and processing of these emulsions a high extensional flow component is present the effect of which on the droplet dynamics is not yet fully understood and characterized. The properties in extensional flow differ from those in shear flow, both flow types determine the rheological behavior of the emulsion. Creating a method to test these properties in extensional flow could lead to a deeper fundamental understanding and aid in the development of emulsions for new generation materials. There is even less research into the dynamics of these droplets in oscillatory extensional flow. The oscillatory extension allows studying of dynamic behavior much like the behavior during processing.

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This graduation project revolves around building the test set-up to create a microfluidic extensional flow and performing experiments on droplets without and with surface modifiers. The microfluidic flow is created with a microfluidic device. The beginnings of the test set-up can be seen in the picture, with a schematic overview of the channels in the microfluidic device. The two opposing flows that are created cause a stagnation point where droplets can be captured and deformed. The flow profile can be found in the second picture.