Silicon array of elongated through‐holes for monodisperse emulsion droplets

Monodisperse emulsions are of great significance in both scientific and industrial fields, since they have advantages such as their better stability and simplified physical properties. A novel micromachined emulsification device has been developed for monodisperse emulsion droplets. It has uniformly sized through-holes, called straightthrough microchannel (MC), on a silicon microchip. An oblong straightthrough MC successfully yielded monodisperse oil-in-water (O/W) emulsion droplets with an average droplet diameter of 32.5 μm and a coefficient of variation below 2% by forcing the dispersed phase into the continuous phase through the straightthrough MC. On the other hand, a circular straightthrough MC yielded polydisperse emulsion droplets. Straightthrough MC emulsification revealed that an elongated cross-sectional shape in the oblong straightthrough MC contributes significantly to the spontaneous formation of monodisperse emulsion droplets without any turbulent mixing.