On Classification of Water-in-Oil and Oil-in-Water Droplet Generation Regimes in Flow-Focusing Microfluidic Devices

The objective of this research work is to propose a phase diagram that can be used to find a proper operating condition for generating droplets of different types. It is found that the phase diagram of Q(R) versus Ca-D can effectively classify the droplet generation into three vivid regimes: dripping, jetting and tubing. For the dripping regime, its operating condition is in the range of either Ca-D < 10(-4) and Q(R) < 50 or 10(-3) < Ca-D < 10(-4) and Q(R) < 1. For the jetting regime, its operating condition is in the range of either Ca-D < 1.35 x 10(-2) and Q(R) > 100 or Ca-D > 1.35 x 10(-2) and Q(R) > 1. For the tubing regime, its operating condition is in the range of Ca-D > 1.35 x 10(-2) and Q(R) < 1.