Geometry-controlled Droplet Generation In Head-on Microfluidic Devices

摘要

We investigated the generation of droplets in a head-on microfluidic device operated with the two identical channels as inlets and the "long leg" as a constriction channel leading to a wider outlet section. For capillary numbers (Ca) of approximately 10~(-5) or less, we find a Ca-independent droplet volume equal to the volume of the constriction channel, which decreases at higher Ca when shear forces become relevant. The droplet generation mechanism is explained in terms of a global capillary instability involving surprisingly stable intermediate surface configurations.