Abstract
Microchannel (MC) arrays with various shapes and sizes were micro-fabricated using a single-crystal silicon substrate. An emulsion is prepared by simply forcing dispersed phase fluid into continuous phase fluid through the MC. Real-time optical observations of the emulsification process can be realized with a microscope video system. The grooved type MC and module were used to characterize MC emulsification, and straight-through MC and module were developed for higher productivity. O/W-emulsions can be obtained due to its hydrophilic surface property after MC oxidation. Hydrophobic MC modified by silanization can be also applicable to W/O-emulsions. Monodisperse emulsions with average droplets sizes ranging 3-90 μm and coefficients of variations lower than 10% have been successfully obtained. Emulsification was significantly affected by MC sizes and structures. Analysis by high-speed camera revealed that the structure of terrace is so important for instability at the outlet, and spontaneous droplet formation caused by interfacial tension. An oblong straight-through MC was highly applicable to emulsification. MC emulsification was also applied to productions of solid-lipid and polymeric microsheres, and microcapsules, showing high availability. The MC emulsification technology has great potential for food, pharmaceutical and chemical industries.
