A method is given for generating droplets in a microchannel network. With oil as the continuous phase and water as the dispersed phase, pico/nanoliter-sized water droplets can be generated in a continuous phase flow at a T-junction. The channel for the dispersed phase is 100 μm wide and 100 μm deep, whereas the channel for the continuous phase is 500 μm wide and 100 μm deep. For given experimental parameters, regular-sized droplets are reproducibly formed at a uniform speed. The diameter of these droplets is controllable in the range from 100–380 μm as the flow velocity of the continuous phase is varied from 0.01 m s⁻¹ to 0.15 m s⁻¹.

In this study, we report the mass production of monodisperse emulsion droplets and particles using microfluidic large-scale integration on a chip. The production module comprises a glass microfluidic chip with planar microfabricated 16–256 droplet-formation units (DFUs) and a palm-sized stainless steel holder having several layers for supplying liquids into the inlets of the mounted chip. By using a module having 128 cross-junctions (i.e., 256 DFUs) arranged circularly on a 4 cm × 4 cm chip, we could produce droplets of photopolymerizable acrylate monomer at a throughput of 320.0 mL h⁻¹. The product was monodisperse, having a mean diameter of 96.4 µm, with a coefficient of variation (CV) of 1.3%. Subsequent UV polymerization off the module yielded monodisperse acrylic microspheres at a throughput of ∼0.3 kg h⁻¹. Another module having 128 co-flow geometries could produce biphasic Janus droplets of black and white segments at 128.0 mL h⁻¹. The product had a mean diameter of 142.3 µm, with a CV of 3.3%. This co-flow module could also be applied in the mass production of homogeneous monomer droplets.