According to many researchers and developers, the discipline of microfluidics will soon reduce chemical manufacturing plants to the size of components that fit in one's hand. These scaled-down processors, known as "microfluidic systems", will have the ability to generate tiny amounts of a given chemical whenever it's needed. Currently, only a few factories exist worldwide that manufacture certain specialized chemicals. With this new technology it's predicted that there will be tens of thousands, perhaps millions, of microfluidic plants manufacturing specialty chemicals in diverse locales.

What makes these microfluidic systems theoretically possible is the behavior of fluid on a microscopic level. The small dimensions of the plant channels that are designed to carry the fluids exhibit what is known as a low Reynolds number, a microfluidics concept that indicates flow mode. Very low Reynolds numbers result in a condition of zero turbulence. In these "micro-channels", where turbulence is absent, mixing is done by diffusion, a very effective technique at the molecular level. An advantage of performing chemistry at this level is the scant quantities of inventory it requires – an arrangement that has many obvious benefits in regards to safety, health and the environment.

One aspect of microfluidic systems that its researchers and developers have yet to agree upon is how best to steer fluids through the system. Understanding the dynamics of electrokinetics is perhaps what holds the key. Electrokinetics falls into two categories: electro-osmosis and electrophoresis. Electro-osmosis exploits the electro-chemical interaction between the fluid and the channel walls, a situation that creates an ionized layer at the edges of the fluid. Applying voltage forces the charged molecules near the wall. This, in turn, pulls the rest of the fluid. Electrophoresis, on the other hand, is the movement of charged molecules through an immobilized gel. With voltage applied, the gel enables smaller molecules to travel more rapidly than larger ones. Both of these electrokinetic techniques can be enacted simultaneously. The relative encouragement of one, or suppression of the other, allows for the tuning of microfluidic systems to handle specified functions.

The burgeoning field of microfluidics has attracted considerable attention from major corporations. Last year, both Hewlett-Packard and Kodak launched projects to develop microfluidic systems with a clear objective of commercializing their results. Hewlett-Packard plans to invest 100 million dollars over the course of five years. They have gone as far as to predict that there will soon be a global market for microfluidic systems worth at least 1 billion U.S. dollars. With the twin forces of scientific research and corporate development at work, widespread use of microfluidic systems may only be a short way off.

Source: Chips with Everything
The Chemical Engineer, Sept. 22, 2000
http://www.tce-online.com/SearchDetail.asp?Union_ShortsArticlesRS_Action=Find(%22ID%22,%22642%22)