Droplet microfluidics

Dielectrophoretic forces depend on the polarizibility of species, rather than on movement of charges [99]. This allows the movement of any type of droplet being immersed by a dielectrically distinct immiscible carrier medium. Since dielectric forces are generated by spatially inhomogeneous fields, no mechanical actuation is required. In addition to this, dielectrophoretic droplet movement benefits from the general advantages given by droplet microfluidic, i.e. discrete, well-known very small volumes, no need for channels, avoidance of dead volumes and more. 

Droplet microfluidics is a science and technology of controlled formation of droplets and bubbles in microfluidic channels. The first demonstration of formation of monodisperse aqueous droplets on chip - in a microfluidic T-junction [1] - was reported in 2001. Since then, a number of studies extended the range of techniques, from the T-junction [2-5], to flow-focusing [6-10] and other geometries [11], and the capabilities in the range of diameters of droplets and their architectures [12-16]. These techniques opened attractive vistas to applications in preparatory techniques [17-19], and - what is the focus of this lecture - analytical techniques based on performing reactions inside micro-droplets. 

C.G. Cooney, C.-Y. Chen, M.R. Emerling, A. Nadim, and J.D. Sterling, Electrowetting droplet microfluidics on a single planar surface. Microfluidics and Nano fluidics 2, 435-446 (2006). 

A. Huebner, M. Srisa-Ait, D. Holt, C. Abell, F. Hollfelder, A. J. deMello, and J. B. Edel, Quantitative detection of protein expression in single cells using droplet microfluidics, Chemical Communications, no. 12, pp. 1218-1220, 2007. 

Fig. 9 Reactions in microdroplets. (a) Schematic showing enhanced mixing and suppressed dispersion in droplets. Reproduced with permission from [47]. (b) Millisecond kinetics on droplet microfluidics. Reproduced with permission from [53]. (c) Droplet-based microfluidic synthesis of anisotropic metal nanocrystals. Reproduced with permission from [94]...

Fig. 10 Droplet microfluidics for microparticle synthesis, (a) Janus particle synthesis by coflowing two monomer streams. Reproduced with permission from [82]. (b) Channel geometry facilitated aspherical particles synthesis. Reproduced with permission from [111], (c) Multiple emulsion templated composite particles synthesis. Reproduced with permission from [112]...

Droplet microfluidics has been a quickly evolving research field in recent years. In... 

Droplet microfluidics is emerging as an attractive platform for biology research [45,46], and it has also been explored in the study of C. elegans in recent years. By using this method, the generated array microdroplets can serve as microreactors and have unique benefits for the flexible and high-throughput operations of individual... 

L. Hung, S. Teh, J. Jester, and A. Lee, PLGA micro/nanosphere synthesis by droplet microfluidic solvent evaporation and extraction approaches, Lab on a Chip, 10, 1820-1825, 2010. 

S. D. Seiffert, Controlled fabrication of polymer microgels by polymer analogous gelation in droplet microfluidics. Soft Matter, 6, 3184-3190, 2010. 

FIGURE 6.11 (a) Droplet microfluidic templating of micrometer-sized droplets... 

BioMEMS) Droplet microfluidics Micro fluo-rescently activated cell sorting (pFACS) Micro total analysis system (pTAS) pTAS... 

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