FIG. 2.

On-demand droplet generator. (a) In the stand-by state, the aqueous phase containing a focused dye stream flows down to waste outlet while most of the oil phase flows into the main channel. Two immiscible phases form a vertical interface and no droplets are generated at the interface. (B) Upon an actuation of the microdispensing pump, pressurized dispensing fluid pushes and forcibly reroutes the dye stream into adjacent oil stream through a small nozzle, producing a droplet due to instability. The droplet is then delivered to injection area. Scale bars represent 100 μm. (Multimedia view) [URL: http://dx.doi.org/10.1063/1.4874715.1]