Microfludics is the study of, and creation of, devices in which the characteristic length dimensions are on the order of microns. At this length scale, the properties of fluids are quite different from what might be intuitively expected based on our understanding of how, say, a hose works, or how water sloshes in a glass. Notably, the Reynolds number (a dimensionless quantity that crudely measures whether viscous forces or inertial forces are dominant in a fluid) is very low, which means that fluids are not turbulent, and do not mix appreciably.
The small dimensions of a microfluidic device have several advantages for applications such as chemical synthesis. Heat control is much easier, because there is less volume to be concerned with. Conditions are much more reproducible for the same reason. Reactions occur more quickly, as the rate limiting step of many reactions is how quickly the reagents can be combined; on the microscale, molecules simply have less distance to travel. Finally, reactions do not have to be altered from bench scale to batch scale - if you want to increase the yield, just add more microreactors.
Automated microfluidic synthesis
Microfluidic reaction optimization is a promising route to automation of a process of optimizing synthetic yield in chemistry. This optimization step is extremely valuable on an industrial scale, but involves tedious tweaking of reaction conditions, and there is no guarantee that the optimization will be valid when scaled up to the large-scale reaction vessels used in industry. Microfluidic reaction optimization on the other hand involves changing reaction conditions on the microscale, which can be done very rapidly. Furthermore, scaling up a microfluidic reaction involves parallelizing the synthesis, meaning that the reaction conditions for one reactor can simply be replicated to thousands.
One of our current research projects involves the development of extremely low-cost miniaturized valves, hundreds of which can be combined in a single device. We're still iterating on the design, but hope to have a paper on it out soon!