ABSTRACT
The miniaturization of chemical ow and analysis systems has opened up exciting avenues of scien ti c and engineering possibilities. Channels with widths in the tens of micrometer range are referred to as micro uidic devices. Fluidic behavior at the microscale may differ from that at larger scales in that interfacial tension, viscous effects, and energy dissipation can dominate the system. Micro uidics has received much attention in the scienti c community and many excellent reviews have been published [1,2]. A key advantage of micro uidics is the ability to perform experiments and bioassays using miniscule quantities of solution. This provides an economic bene t and is important for certain biosensing applications, experiments requiring single-molecule interrogation
(e.g., deoxyribonucleic acid (DNA) sequencing [3,4]), or diffusion-limited regimes. Another bene t is that rapid measurements of these minute quantities can be performed with miniaturized analytical systems [5-7]. In some applications slow or minimal mixing is required, and the laminar ows obtained in microchannels become highly desirable. Water-in-oil emulsions can be formed in micro uidic devices to form a steady stream of monodisperse aqueous droplets with volumes as small as picoliters [8]. The drops can be loaded with reactants to perform chemical reactions of interest [9].
