Photolithographic micromachining of
silicon is a candidate technology for the construction of high-throughput
DNA analysis devices. However, the development of complex
silicon microfabricated systems has been
hindered in part by the lack of a simple, versatile pumping method for integrating individual components. Here we describe a surface-tension-based
pump able to move discrete nanoliter drops through enclosed channels using only
local heating. This thermocapillary
pump can accurately mix, measure, and divide drops by simple electronic control. In addition, we have constructed thermal-cycling chambers,
gel electrophoresis channels, and radiolabeled
DNA detectors that are compatible with the
fabrication of thermocapillary
pump channels. Since all of the components are made by conventional
photolithographic techniques, they can be assembled into more complex integrated systems. The combination of
pump and components into self-contained miniaturized devices may provide significant improvements in
DNA analysis speed, portability, and cost. The potential of microfabricated systems lies in the low unit cost of silicon-based construction and in the efficient sample handling afforded by component integration.
