Research Highlights

Microdroplet Technology

Droplet-based microfluidics has recently been applied to a wide range of applications, including biological assay, combinatorial synthesis, and high-throughput screening. In particular, microdroplets of pico- to nanolitre volumes are capable of enclosing various biological soft matter. Unlike solid wells, they are a more active system, and can move or stop, split or merge with others, and select different paths for sorting at timed intervals. For example, microfluidic abacus channels are demonstrated for the sequential addition of droplets at the desired location [Lab Chip 2009, 9, 207]. A precise temporal control of microdroplets such as synchronization and combinatorial pairing of droplets is also required to achieve a variety range of chemical and biochemical reactions inside microfluidic networks [Biomicrofluidics 2011, 5, 034117]. Recently, we reported a single-cell-based assay using a mesh-integrated microwell array which enables easy trapping and consistent addition of droplets in a high-throughput manner [Lab Chip 2012, 12, 1594]. The mesh-integrated droplet array provides a microfluidic platform for simple storage and on-demand merging of droplets. The openness of the system allows easy access to individual droplets and variable integration with other functional modules. By integrating the single-cell droplet-generating channel, the mesh-integrated microarray allows immediate confinement of single cells and total isolation of each chamber throughout the entire droplet manipulation process. With further development, this device may provide a novel screening platform, especially for various microbes directly harvested from a natural environment.

Related Articles:  

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Youn-Hee Park, Do-Hyun Lee, Eujin Um, Je-Kyun Park, "On-chip generation of monodisperse giant unilamellar lipid vesicles containing quantum dots," Electrophoresis, 37 (10), 1353-1358 (2016).  
External link Selected in the virtual issue of Electrophoresis dedicated to Nanoanalysis  

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Do-Hyun Lee, Miran Jang, Je-Kyun Park, "Rapid one-step purification of single-cells encapsulated in alginate microcapsules from oil to aqueous phase using a hydrophobic filter paper: Implications for single-cell experiments," Biotechnol. J., 9 (10), 1233-1240 (2014).  
External link Supporting Info. (pdf, 361 KB)

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Do-Hyun Lee, Je-Kyun Park, "Reduction in microparticle adsorption using a lateral interconnection method in a PDMS-based microfluidic device," Electrophoresis, 34 (22-23, 3119-3125 (2013).  

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Do-Hyun Lee, Chae Yun Bae, Jong-In Han, Je-Kyun Park, "In situ analysis of heterogeneity in the lipid content of single green microalgae in alginate hydrogel microcapsules," Anal. Chem., 85 (18), 8749-8756 (2013).   
External link Supporting Info. (pdf, 455.8 KB )

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Jisun Lee, Myung Gwon Lee, Cheulhee Jung, Youn-Hee Park, Chaeyeon Song, Myung Chul Choi, Hyun Gyu Park, Je-Kyun Park, "High-throughput nanoscale lipid vesicle synthesis in a semicircular contraction-expansion array microchannel," BioChip J., 7 (3), 210-217 (2013).   The first two authors contributed equally to this work.  

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Joonwoo Jeong, Eujin Um, Je-Kyun Park, Mahn Won Kim, "One-step preparation of magnetic Janus particles using controlled phase separation of polymer blends and nanoparticles," RSC Adv., 3 (29), 11801-11806 (2013). 
External link Supporting Info. (pdf, 124 kB)

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Eujin Um, Eugene Rha, Su-Lim Choi, Seung-Goo Lee, Je-Kyun Park, "Mesh-integrated microdroplet array for simultaneous merging and storage of single-cell droplets," Lab Chip, 12 (9), 1594-1597 (2012).   
External link
Supporting Info. (pdf, 349K; movie 1, 1063K; movie 2, 2887K)

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Do-Hyun Lee, Wonhye Lee, Eujin Um, Je-Kyun Park, "Microbridge structures for uniform interval control of flowing picoliter droplets in microfluidic networks," Biomicrofluidics, 5 (3), 034117 (2011).  
External link Selected for Vir. J. Nan. Sci. & Tech. (2011)/ Volume 24 / Issue 9 / MICROFLUIDICS AND NANOFLUIDICS (2011. 8. 29)
External link Selected for Vir. J. Bio. Phys. Res. (2011)/ Volume 22 / Issue 5 / INSTRUMENTATION DEVELOPMENT (2011. 9. 1)

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Eujin Um, Seung-Goo Lee, Je-Kyun Park, "Random breakup of microdroplets for single-cell encapsulation," Appl. Phys. Lett., 97 (15), 153703 (2010).

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Do-Hyun Lee, Hyundoo Hwang, Je-Kyun Park, "Generation and manipulation of droplets in an optoelectrofluidic device integrated with microfluidic channels," Appl. Phys. Lett., 95 (16), 164102 (2009).    The first two authors contributed equally to this work

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RSC’s Chemical Technology news magazine
(November 21, 2008)

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Eujin Um, Je-Kyun Park, "A microfluidic abacus channel for controlling the addition of droplets," Lab Chip, 9 (2), 207-212 (2009).
External link
Supporting Info.: mpg Movie 1 (3.28 MB), Movie 2(5.53 MB), Movie 3 (4.19 MB)
External link Selected as one of the ten most accessed Lab on a Chip articles in January

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Eujin Um, Dae-Sik Lee, Hyun Bong Pyo, Je-Kyun Park, "Continuous generation of hydrogel beads and encapsulation of biological materials using a microfluidic droplet-merging channel," Microfluid. Nanofluid., 5 (4), 541-549 (2008).