Number controllable active microdroplet merging with wide range of volume for digital chemical synthesis

This paper presents microdroplet merging device which can actively control the number of merged microdroplets with a wide range of volume under various flow conditions. Independently generated two different droplets are trapped at pillar structure and its trapping time is controlled by horizontal pneumatic micro actuators. The droplet merging of multi-mode from no-merging to 4 droplets merging is successfully achieved with a simple single layer PDMS (polydimethylsiloxane) device. The micro pneumatic actuators widen a range of applicable droplet size with deformed channel width, as well as switching the merging mode with trapping time control.