Abstract: A microfluidic network comprising a plurality of droplet emitters forming droplets of a first fluid in a second fluid immiscible in the first fluid to produce an outlet stream of droplets, wherein each of the emitters are in fluid communication with each other via the network and all have an auto-synchronised droplet formation frequency by hydrodynamic interaction between the emitters is provided. The synchronisation gives a surprisingly narrow droplet size distribution for the network.