Droplet Formation in Flow Invariant Geometry for Parallel Processing

We have designed a microfluidic geometry that forms the same size droplets over a wide range of capillary numbers and flow rate ratios.  Stereolithographic printing replicates the three dimensional geometry to easily produce cheap devices without the need for conventional soft- and photolithography.  Using a single device geometry, we can produce droplet sizes spanning over two orders of magnitude.  Additionally, the frequency of droplet formation is in the kHz range.  This basic unit of operation is applied to create highly parallelized systems for high-throughput operations.  Parallel configurations of these geometries produced linear increases in throughput while remaining insensitive to small changes in volumetric flow rates.  Traditional issues with parallel systems, including maintaining a constant resistance across each parallel channel, were alleviated due to the flow invariant geometry, creating a robust parallel system.  For multi-step reactions, we can operate the basic droplet formation units in series to achieve multiple reagent additions.  The facile operation and fabrication of these devices will allow a wide audience of researchers to use droplet devices in encapsulation, synthesis, and purification applications.  We perform nanoparticle syntheses in these devices.