Microfluidic devices flow-focusing

Garstecki, P., Gitlin, I., DiLuzio, W., Whitesides, G.M., Kumacheva, E. and Stone, H.A. (2004). Formation of monodisperse bubbles in a microfluidic flow-focusing device. Appl Phys. Lett. 85,2649-2651. 

Figure 5. The simple periodic mode of a flow-focusing device illustrated on five micrographs taken during the period of formation of a single bubble in this microfluidic flow-focusing device [15].

Figure 6. Experiments on time-resolved tracking of the shape of the gas-liquid interface during the process of formatiorr of a single bubble in a microfluidic flow-focusing device. From a video recording of the process of break-up, we extract the projection of the interface on the x-y plarre (plane of the microfluidic device). We then extract the minimum width of the neck as a functiorr of time (Adapted Ifom Ref [21]).

Figure 9. Formation of droplets in microfluidic flow-focusing devices. The micrographs on the left illustrate the process of formation of aqueous drops in an organic continuous fluid [S. Makulska, P. Garstecki, Institute of Physical Chemistry PAS]. The chart on the right shows the dependence of the volume of liquid droplets formed in a planar flow focusing device on the value of the capillary number (Adapted from Ref [24]).

M. Hashimoto, P. Garstecki, and G.M. Whitesides, Synthesis of composite emulsions and complex foams with the use of microfluidic flow-focusing devices, Small, 3, 1792-1802, (2007). 

H.A. Stone, Formation of monodisperse bubbles in a microfluidic flow-focusing device. Applied Physics Letters, 85, 2649-2651, (2004). 

M.T. Sullivan and H.A. Stone, The role of feedback in microfluidic flow-focusing devices. Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences, 366,2131-2143, (2008). 

Q. Xu, M. Hashimoto, T. Dang, T. Hoare, D. Kohane, G. Whitesides, and R. Danger, Preparation of monodisperse biodegradable polymer microparticles using a microfluidic flow-focusing device for controlled drug delivery, Small, 5, 1575-1581, 2009. 

Bon and Kumacheva and coworkers [104] demonstrated that monodisperse solids-stabilized droplets could be generated in a microfluidic flow focusing device, whereby the solid particles were initially present in the dispersed phase. Polymerization of the monomer droplets led to hybrid polymer microspheres. They also showed that non-spherical particles could be obtained by geometric confinement of the droplets in the channel [104,105]. 

Fig. 25.11 Schematics depicting two mechanisms of droplet foimation in a microfluidic flow focusing device (FFD) (Reprinted from [43]. With permission. Copyright 2007 the Royal Society of Chemistry)...

M.W. Weber, R. Shandas, Computational fluid dynamics analysis of microbubble formation in microfluidic flow-focusing devices, Micrcfluidics Nanojluidics, 2007, 3, 195-206. 

S.L. Anna, Fl.C. Mayer, Microscale tipstreaming in a microfluidic flow focusing device, Phys. Fluids, 2006, 18. 121512. 

The very first flow focusing device was developed by Stone and coworkers [11] and was used for the emulsification of water in silicone oil. The geometry of this device is depicted in Figure 18.7 and was obtained after replication of a positive relief of the microchannels patterned in SU-8 photoresist. The authors named this FFD a microfluidic flow focusing device (MFFD). A few years after the development of this microsystem, Kumacheva and coworkers [12] used an MFFD (Figure 18.7, top left) made out of PDMS or polyurethane (PU) for the emulsification and polymerization of several multifunctional acrylates ethylene glycol dimethacrylate (EGDMA),... 

Ward T, Paivre M, Stone HA Drop production and tip-streaming phenomenon in a microfluidic flow-focusing device via an interfacial chemical reaction, Langmuir26 9233—9239,... 

K. Keohane, D. Brennan, P. Galvin, B.T. Griffin. Silicon microfluidic flow focusing devices for the production of size controlled PLGA based drug loaded microparticles. Int J Pharm 467, 60-69, 2014. 

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