Flexible Fractal Integration of Microfluidic Modules for Controllable Mass Production of Monodisperse Microdroplets

Modular microfluidic integration, which is powerful forcontrollablemass production of droplets, usually suffers from limited dimensionchoice and complicated calculations. Here, a generalized and simplestrategy based on stepwise nesting of basic fractal networks to createnested flow distribution networks for modular microfluidic integrationis proposed. The H-shaped fractal network with a symmetrical flow-resistancesetup and the widely used ladder network are respectively used asthe typical basic fractal network and the control group. Comparedto the control group, the nested fractal networks enable more flexiblechoices of microchannel dimensions for uniform flow distribution.The integrated fractal modular device with 256 flow-focusing microchannelscan massively produce droplets with size monodispersity remarkablybetter than those from the control group device and can create monodisperseCa-alginate microspheres from viscous liquids. This strategy providesa rational scale-up guideline to create modular devices with uniformflow distributions for mass production of monodisperse microdroplets.