Novel Microfluidic Device for the Preparation of Multiple Microproducts

Double-layered microbubbles, microdroplets, and a mixture of microproducts were fabricated by a novel device of the geometric combination of a Y-junction and a flow-focusing junction in this study. An air-in-oil-in-water microbubble was used as a template for the preparation of double-layered microbubbles. The oil-in-water microdroplets and multiple microproducts could be generated in this system at the same time. To observe the evolution of the multiphase flow in a microchannel, high-speed microscopy and digital imaging technologies were applied. The fluidic mechanisms of generating specific microproducts under different operating conditions were investigated through the analysis of the flow patterns. The analysis of the microproduct generation process showed that operating conditions such as the air pressure and oil- and aqueous-phase flow rates had a significant impact on the size, generation frequency, and monodispersity of the microproducts. Dimensional analysis was applied to predict the diameters of the microproducts and showed a good agreement. Finally, the method to promote the emulsion stability was obtained.