Novel microfabricated nozzle array with grooves for microdroplet generation

A novel micronozzle array with grooves was specially designed for high-throughput microdroplet generation and high-efficiency mixing of heterogeneous systems without surfactants. The microgrooves, with a width of 25 μm between micropores, could significantly prevent the dispersed phase from spreading on the membrane surface and reduce the microdroplet size and polydispersity at sufficiently high fluxes of the dispersed phase. Through different oil–water systems, the effects of flow conditions, system physical properties, and flow patterns on droplet size were investigated in the micronozzle array device. Under the jetting flow pattern, the n-hexane, dichloromethane , and ethyl acetate droplets could obtain average diameters of 35 μm, 31 μm, and 24 μm, respectively, and the coefficient of variation was between 20% and 40%. The dripping and jetting flow regions were demarcated to fully understand the transition of the flow pattern. Furthermore, a droplet size prediction model was established based on force equilibrium. The micronozzle array proposed in this work has great potential for future practical applications.