Pickering emulsion is a liquid/liquid system stabilized by nano-particles. Microfluidic technology is an important method for preparing monodispersed Pickering emulsions. The droplet coalescence rule for the working system containing nano-particles is a core scientific issue for proceeding this new method. Using n-octanol and water as the continuous and dispersed phases respectively

the droplet collision processes in a broadening microchannel with a hexagon shape were investigated. Three typical flows (droplet coalescence

contact without coalescence and contactless) were confirmed. The effects of flow rate

nano-particle concentration and wetting property of nano-particles on the droplet coalescence percentage were studied. In addition

the working mechanism of nano-particles in the liquid film drainage processes were analyzed.