(236h) Hydrodynamic Self-Rectification: A Novel Mechanism for Generating Uniform Droplet Arrays In a Microfluidic Network

We report a novel mechanism for generating monodisperse microfluidic droplet arrays. When a train of surfactant-free confined droplets are introduced into a fluidic network with hydrodynamic traps, the droplets are immobilized in the traps due to collective hydrodynamic resistive interactions. In the event, that an immobilized drop either under-fills or overfills the trap, we find that subsequent drops rectify its volume through coalescence, followed by break-up. This self-rectification mechanism thus yields highly monodisperse static droplet arrays. We also find that this unique mechanism persists over a broad range of flow rates. We further illustrate the flexibility of this method by generating multiplexed microfluidic arrays. Our study exemplifies the ability to harness microscale collective hydrodynamic phenomena between confined deformable particles to perform autonomous tasks in microfluidic devices.