Droplet-Based Microfluidics for Biological Sample Preparation and Analysis

This chapter focuses 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. A straightforward method for microdroplet incubation is to simply increase the channel length following droplet generation, but increased back pressure and disruption of droplet formation can quickly become an issue. To date, in-droplet fluorescence detection remains the most widely used method for analyzing the contents of droplets due to its ability to measure in real time and with high sensitivity. Droplet-based microfluidics has developed substantially as a technology and will likely assume a higher-profile role in biological analyses in the future. A number of operational units have been well developed for droplet-based microfluidics, including droplet generation, fusion, and incubation. Others, such as droplet extraction for subsequent analysis of the contents, have been developed recently and promise to add versatility to the platform.