| In the talk I will discuss the fundamental and applied aspects of flow of droplets in microchannels. The fundamental questions include the apparently simple problem of predicting the speed of a droplet provided the cross-section of the fluidic duct, the viscosities of the droplet liquid and the continuous fluid, the interfacial tension between them and the rate of flow of the carrier liquid. Automated experiments allow to characterize in detail the complex dynamics of this simple system and to uncover an unexpected change of the topology of the field of flow inside the droplet upon a change of its speed. I will also show the use of the capillary effects and of the bypassing flow of the continuous liquid around the droplets in construction of geometric microfluidic modules that allow to trap, meter, merge, shift and array droplets completely passively, with minimum requirements on the precision of operating the device, while execute precise liquid-handling protocols. |
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