Authors: S. Hardt
Affilation: Darmstadt University of Technology, Germany
Pages: 567 - 570
Keywords: microfluidics, lab-on-a-chip, design concepts
This paper reviews and compares different strategies for designing and building up microfluidic systems, with a special emphasis on the system aspect as opposed to single components capable of performing only special operations. An overwhelming number of microfluidic components have been reported in the literature in the past few years, but convincing concepts to integrate those components to a unit performing complex microfluidic operations seem to be quite rare. Opposed to such bottom-up approaches there are some concepts of top-down character, in which a rather monolithic system is able to perform a number of complex operations. Another competition occurs between continuous-flow and droplet-based systems. Droplet-based microfluidics is a quite attractive concept when small sample amounts need to be processed in a well-defined manner. However the physics of moving droplets is much more involved than that continuous flow. Correspondingly, the design and simulation of droplet-based microfluidic systems poses considerable challenges, and effects such as contact-angle hysteresis can make a well-controlled transport of such droplets quite difficult. The last major competition considered here is that between pressure-driven flow and electrokinetic flow, possibly the two most popular concepts for fluid transport on the microscale. In this work the current status of the competition between different paradigms in microfluidics is reviewed, and the advantages and disadvantages of the approaches are compared. It is hoped that by virtue of such an analysis of the state-of-the-art in microfluidics, future directions might become clearer.