Effect of microchannel structure on droplet size during crossflow microchannel emulsification

A monodispersed oil-in-water emulsion was continuously produced using a crossflow-type silicon microchannel plate in which a liquid flow path for the continuous phase was made, and on each side of the wall of the path, an array of regular-sized slits (microchannels) was precisely fabricated on a micrometer scale by photolithography. A flat glass plate was tightly attached to the microchannel plate to cover the top of the microchannels. Regular-sized oil (triolein) droplets were generated by pressing the oil through the microchannels into a continuous phase of 0.3 wt% aqueous sodium lauryl sulfate. The average size of the oil droplets was regulated within a range of 11.3 to 28.2 μm by changing the microchannel structural features such as the shape of the cross section and outlet, the equivalent diameter, and the length of the terrace, which is a flat area fabricated at the outlet of the microchannels. In every case, the droplet size distribution was narrow, and the geometric standard deviation was 1.03 or less.