ABSTRACT
Droplet-based microfluidics, in which reagents of interest are compartmentalized within femtoliter-to-nanoliter-sized aqueous droplets or plugs that are encapsulated and dispersed in immiscible oil phase, has emerged as an attractive platform for small-volume bioanalysis. This chapter focuses primarily on the integrated droplet-based microsystems having the ability to couple with chemical separations and nonoptical detection, allowing for ex situ analysis and identification of the biochemical components contained in the microdroplets. Most planar microfluidic droplet generators are designed using T-junction and flow-focusing geometries, in which small droplets are spontaneously formed at an intersection taking advantage of the interface instability between oil and aqueous streams. Kelly et al. invented a droplet extraction interface, which was constructed with an array of cylindrical posts to separate the segmented flow channel and the continuous aqueous phase channel. Droplet-based microfluidics has developed substantially as a technology and will likely assume a higher profile role in biological analyses moving forward.
