Effect of nozzle width on droplet formation in wedge-shaped step-emulsification microchannel devices

The effect of nozzle width on the droplet formation in the wedge-shaped step microchannel devices was investigated, and the applicability of the devices with different nozzle widths were evaluated in generating droplets with various viscosities. The glycerol aqueous solution with different viscosities and silicone oil were used as the dispersed phase and the continuous phase, respectively. The dripping, transition, and jetting flow patterns were found in the experiment and the dripping flow was mainly discussed. The effect of the nozzle width, the flow rates, and the viscosities of the dispersed phase on the droplet size, the formation frequency, the size-stable range, and the variation coefficient of the droplet diameter were discussed. In addition, the effect of nozzle width on droplet formation dynamics was analyzed. An empirical formula for the influence of nozzle width and dispersed phase viscosities on the average stable size of droplets generated in size-stable zones was proposed.