Microfluidic methods for generating continuous droplet streams

Abstract

Microfluidic technologies have emerged recently as a promising new route for the fabrication of uniform emulsions. In this paper, we review microfluidic methods for synthesizing uniform streams of droplets and bubbles, focusing on those that utilize pressure-driven flows. Three categories of microfluidic geometries are discussed, including co-flowing streams, cross-flowing streams, and flow focusing devices. In each category we summarize observations that have been reported to date in experiments and numerical simulations. We describe these results in the context of physical mechanisms for droplet breakup, and simple theoretical models that have been proposed. Applications of droplets in microfluidic devices are briefly reviewed.

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…16), which is the mostly utilized geometry in microfluidics. Dripping-jetting transition is generally explained by dimensionless numbers such as capillary, Weber and Reynolds numbers, for which we refer to other literature [179,[199][200][201]. In this review however, we would like to explain dripping-jetting transition by using parameters that are familiar to chemists, such as flow rates, polarity differences, viscosity, wettability and channel dimensions.…”

Droplet formation in microfluidic cross-junctions

“…Microdroplet technology has recently emerged as a promising flexible platform for microfluidic functions. [1][2][3][4] The miniaturization of entire process enables the rapid analysis of very small quantities of samples in a portable, automated, and inexpensive format. 3 Recently, microdroplet technology has been used as microreactors for chemical analysis and protein crystallization, 5,6 as molds for curing polymeric microspheres.…”

“…[1][2][3][4] The miniaturization of entire process enables the rapid analysis of very small quantities of samples in a portable, automated, and inexpensive format. 3 Recently, microdroplet technology has been used as microreactors for chemical analysis and protein crystallization, 5,6 as molds for curing polymeric microspheres. 7,8 Furthermore, programmable fluidic assays for sampling glucose concentration of human physiological fluids 9 and DNA analysis 10 have been individually demonstrated using microdroplet system.…”

Emulsification in a microfluidic flow-focusing device: effect of the viscosities of the liquids

“…Most commonly used microemulsification devices include T-junctions (Christopher and Anna 2007;Dreyfus et al 2003;Link et al 2004;Nisisako et al 2002;Thorsen et al 2001;Garstecki et al 2006), flow-focusing devices (Anna et al 2003;Ganan-Calvo 1998;Ganan-Calvo and Gordillo 2001;Xu and Nakajima 2004;Garstecki et al 2004), and devices in which liquid threads break on the terraces of microchannels (Sugiura et al 2001(Sugiura et al , 2002a. Since the generation of droplets with a predictable and reproducible size and size distribution determines their potential applications (including the synthesis of polymer colloids), several research groups have explored various aspects of the process of emulsification (Seo et al 2005a;Xu et al 2005;Zhang et al 2006;Cygan et al 2005;El-Ali et al 2005;Garstecki et al 2005a;Hudson et al 2005;Jensen and Lee 2004;Khan et al 2004;Song et al 2003;Zheng and Ismagilov 2005;Zheng et al 2003) .…”