Droplet Encapsulation And Sorting Based-on Microfluidic Chip

Droplet-based microfluidic systems have shown promises on high-throughputencapsulation and screening of single cells or organisms. However, the encapsulationefficiency is limited by randomness that follows Poisson distribution, resulting in largeportions of empty droplets. Thus, separation of droplets is necessary to improve the purityof encapsulated cells. Recently, microfluidic-based droplet sorting have been realizedusing dielectrophoresis, electroosmosis and acoustic wave. However, none of them haveachieved high separation efficiency, purity or good biocompatibility simultaneously.In this study, we reported the integration of droplet generation and sorting in amicrofluidic chip using hydrodynamic force. With2.0%(m/v) sodium alginate solution asdispersed phase, hexadecane containing3.0%(v/v) Span80as continuous phase, dropletgeneration was realized by hydrodynamic focusing. Separation of droplets was achievedby hydrodynamic gated injection based-on the result of fluorescence detection. The assaysof isolation of encapsulated polystyrene beads and Hela-DsRed cells were completerespectively, and both of the sorting purities were more than99%.In addition, we established a novel method for selective droplet generation. Thisapproach broke the radomness of droplet encapsulation, and made droplet encapsulationand sorting as one process. Polystyrene microspheres and Hela-DsRed cells were selectiveencapsulated respectively, and a well encapsulation rates about90%were obtained.