Self-synchronizing pairwise production of monodisperse droplets by microfluidic step emulsification

Abstract

The in situ generation of pairs of droplets with excellent monodispersity is essential for quantitative (bio-)chemical reactions in a droplet based microfluidic chip. In the present paper, we demonstrate the simultaneous self-synchronized production of droplets with two different contents by step emulsification. The synchronization is achieved by a pressure cross talk of two connected production units while retaining all relevant properties of a single-step-emulsification unit. Pairs and triplets of droplets can be achieved. While the drop volumes of the two droplet types may be different up to a factor of 2, the excellent monodispersity of each type is retained.