Prediction of droplet sizes in a T-junction microchannel: Effect of dispersed phase inertial forces

The generation of monodispersed droplets in T-junction microchannels has wide range applications in biochemical analysis and material synthesis. While the generation of these monodispersed droplets was previously considered to be a balance between forces acting from continuous phase and interfacial force, it is shown here that the inertial force from the dispersed phase also plays an important role in determining the size of the generated droplets. A theoretical analysis for the size of monodisperse droplets generated in a microfluidic T-junction device is developed, and it is validated with a large set of experimental observations. The theoretical analysis accounts for the inertial forces from the dispersed phase along with the forces from the continuous phase and the interfacial forces to define the non-dimensional numbers that govern the droplet breakup in the T-junction microchannel.