Simplified Mesofluidic Systems for the Formation of Micron to Millimeter Droplets and the Synthesis of Materials

We present and validate simple mesofluidic devices for producing monodisperse droplets and materials. The significance of this work is a demonstration that simple and complex droplet formulations can be prepared uniformly using off-the-shelf small-diameter tubing, barbed tubing adapters, and needles. With these simple tools, multiple droplet-forming devices and a new particle concentrator were produced and validated. We demonstrate that the droplet-forming devices could produce low-dispersity particles from 25 to 1200 μm and that these results are similar to results from more complicated devices. Through a study of the fluid dynamics and a dimensional analysis of the data, we have correlated droplet size with two dimensionless groups, capillary number and viscosity ratio. The flow-focusing device is more sensitive to both parameters than the T-junction geometry. The modular character of our mesofluidic devices allowed us to rapidly assemble compound devices that use flow-focusing and T-junction devices in series to create complex droplet-in-microcapsule materials. This work demonstrates that flow chemistry does not require complicated tools, and an inexpensive tool-kit can allow anyone with interest to enter the field.