ABSTRACT
This chapter describes the programmable active microfluidic droplet generation approach and devices that the authors have developed. It discusses the applications to single-cell genetic analysis of pathogens and mammalian cells. Droplet microfluidics has been typically a passive process, consisting of droplet generation by flow focusing and cross-flow shearing, and downstream manipulation based on hydrodynamic interactions of droplets. Microfluidic droplet technology is particularly advantageous for single-cell analysis because it facilitates rapid statistical compartmentalization of targets for massively parallel pico- to nanoliter-scale assays. Single cells are microfluidically encapsulated together with primer-functionalized beads in uniform agarose droplets. When the droplets are cooled, the agarose droplet forms a rigid but porous gel bead to protect the individual cell and its genomic DNA while allowing fluidic access to enzymes and chemicals for cell lysis, washing, and polymerase chain reaction (PCR).
