Effects on droplet generation in step-emulsification microfluidic devices

Y Step emulsification technology is an important breakthrough for the industrial application of microfluidic devices. In this paper, the influences of microdevice structures and physical properties of fluids on the droplet (around 1 mm in size) generation in a step emulsificator with a single microchannel are studied. Through the analysis of the interface evolution process during droplet generation, we found that increasing the width of the terrace (0.4-1.0 mm) and the size of the collection cavity, decreasing the viscosity of the dispersed phase (0.89-54.61 mPa.s) result in the increase in the range of the dripping flow regime, obtaining a larger emulsion flux of the microdevice. The prediction equation for the droplet size is proposed by considering the inertial and viscous forces of the dispersed phase: D/h= 1.63Oh(0.17)We(0.14) + D-0/h(0.47)Oh(0.24). Finally, the relationship between the satellite droplet size formed by the neck rupture and the manipulation variables is presented. (C) 2021 Elsevier Ltd. All rights reserved.