Large microchannel emulsification device for mass producing uniformly sized droplets on a liter per hour scale

We report the mass production of uniformly sized droplets on a liter per hour scale using a large microchannel (MC) emulsification device developed in this study. This MC emulsification device includes a newly designed 40 x 40-mm silicon MC array chip with 24,772 asymmetric MCs, each consisting of a circular microhole (17-mu m diameter and 200-mu m depth) and a microslot (17 x 119-mu m cross-section and 60-mu m depth). The oil-in-water (O/W) system was composed of n-tetradecane as the dispersed phase and a Milli-Q water solution containing 2.0 wt% Tween-20 as the continuous phase. The MC emulsification results demonstrated the stable mass production of uniformly sized oil droplets with average diameters of 87 mu m and coefficients of variation below 2% over a wide range of volumetric flow rates of the dispersed phase up to 1.4 l/h. Analyses of shear stress at the chip surface and droplet generation via an asymmetric MC verified that the resultant droplet size and size distribution was not influenced by the volumetric flow rate of each phase. The large MC emulsification device has a potential droplet productivity exceeding several tons per year, which could satisfy a minimum industrial-scale production of monodisperse microdispersions containing emulsion droplets, microparticles, and microcapsules.