Control of Pressure-Driven Microdroplet Formation and Optimum Encapsulation in Microfluidic System
Formation of stable micro-droplets in multiphase flow is an important step to perform numerous microfluidic applications such as sorting experiments. We herein investigate the conditions of formation of stable micro-droplets using a flow focusing microfluidic device. Two single phases and four different multiphase flow regimes were observed depending on the pressures of fluids. By tuning sample stream pressure against fixed lower oil stream pressure, stable droplet regime can create microenvironment with a diameter ranged from 30 µm to 140 µm. Results obtained show that the formation of strictly size controlled droplets can encapsulate single cell-sized bead into droplet. Moreover, the limit between unstable and stable droplet regimes was the most suitable to efficiently encapsulate cell-sized bead in droplet sorting application. This limit can be precisely monitored by using the change of the droplet speed found at the threshold between these two regimes.
KeywordsMicrofluidics Encapsulation Flow control
This work was supported by Kanagawa Prefector’s local basic science funding for the On-chip Cellomics Project at the Kanagawa Academy of Science and Technology. This research was also supported by JST, CREST. We gratefully thank Ms. H. Mikami and Ms. M. Hasegawa for their helps during the experiments.
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