in a co-flow microfluidic device with coaxial arrangement, the dispersed phase is injected from an inner capillary into a tube, in which there is a parallel flowing stream of the continuous phase. When both fluids flow at low rates, single almost monodispersed droplets are formed. This process is defined as dripping. When the flow rate of either fluid is increased, a wider size distribution droplet is gener- ated, due to the jet formation