Electrowetting-enhanced microfluidic device for drop generation

We integrated electrowetting into a microfluidic flow focusing device to study drop generation under the influence of electric fields. Using both the dispersed phase inlet pressure and the applied voltage as control parameters, we find that the range of drop sizes and the drop generation rate can be controlled in a much finer way than with hydrodynamics alone. In particular a conical spray regime occurring at a voltage of O(50 V) allows for continuous tuning of the (highly monodisperse) drop diameter from approximate to 5 to 50 mu m at a fixed continuous flow rate.