Microfluidic chemical analysis systems

The field of microfluidics has exploded in the past decade, particularly in the area of chemical and biochemical analysis systems. Borrowing technology from the solid-state electronics industry and the production of microprocessor chips, researchers working with glass, silicon, and polymer substrates have fabricated macroscale laboratory components in miniaturized formats. These devices pump nanoliter volumes of liquid through micrometer-scale channels and perform complex chemical reactions and separations. The detection of reaction products is typically done fluorescently with off-chip optical components, and the analysis time from start to finish can be significantly shorter than that of conventional techniques. In this review we describe these microfluidic analysis systems, from the original continuous flow systems relying on electroosmotic pumping for liquid motion to the large diversity of microarray chips currently in use to the newer droplet-based devices and segmented flow systems. Although not currently widespread, microfluidic systems have the potential to become ubiquitous.