Water-in-oil emulsions were produced in microchannels with Y- and T-junction geometries by individual droplet generation. For each microchannel configuration, the effect of the fluids and interface properties as well as of the process conditions was evaluated. The size of the droplets depended mainly on the relative velocity between continuous and dispersed phases and the relative fluid viscosity between phases. Those variables were related to the shear stress between the phases, which caused the droplet detachment. In addition, the interfacial forces played a minor role in Y-junction, and they had no effect in the droplets formation in T-junction microchannels. In Y-junction, a large variation in the droplet size was observed, depending on the system composition and the operating conditions. At low relative velocity and fluid viscosity, no droplets were generated. In contrast, the process in T-junction resulted in a lower variation of droplets size and the droplets were formed even at less favorable conditions. Such results indicate that the knowledge of the mechanism of droplets generation in each microchannel geometry makes it possible to choose the appropriate configuration according to the type of fluid, and the operating conditions can be adjusted to obtain the desired final emulsion.
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The authors appreciate the technical support given by Professor Angelo Gobbi and Maria Helena de Oliveira Piazzeto of the Microfabrication Laboratory at the Brazilian Center for Research in Energy and Materials (CNPEM). The authors also would like to thank São Paulo Foundation (FAPESP 2009/54.137-1, 2010/16.708-4 and 2011/06.083-0) and National Council for Scientific and Technological Development (CNPq 304611/2009-3) for supporting this research.
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Ushikubo, F.Y., Birribilli, F.S., Oliveira, D.R.B. et al. Y- and T-junction microfluidic devices: effect of fluids and interface properties and operating conditions. Microfluid Nanofluid 17, 711–720 (2014). https://doi.org/10.1007/s10404-014-1348-4
- Microfluidic devices
- Droplet generation
- Y-junction microchannel
- T-junction microchannel