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S. W. Turner and H. G. Craighead
School of Applied and Engineering Physics, Cornell University, Ithaca, NY
Nanofabricated solid-state structures provide an avenue for investigating fundamental
aspects of DNA electrophoresis in a 2-d sieving matrix, as a potential DNA separation technology
and other applications for controlling the flow of small volumes of fluid
A new technique has been devised to create monolithic 2-d solid state sieving structures for DNA
electrophoresis which incorporate a built-in capping layer constructed using thin-film processing
techniques. Unlike previous sealing methods, the gap can be controlled precisely because it is
determined by the thickness of a sacrificial layer, which is later removed. Obstructions are
lithographically defined, and transferred to the sacrificial layer with RIE. A silicon nitride
capping layer is deposited over the sacrificial layer and perforated to allow removal of the
sacrificial layer with a wet chemical etch. The irrigation holes are then re-sealed.
The technique is extensible over a range of gap thicknesses from several microns to a few
nanometers, and is limited laterally only to the resolving power of available lithography
techniques. The method allows multiple layers with vertical interconnects.
The inherent precision and convenience of the monolithic design will simplify the integration
of optical and electronic devices. These attributes make the technique well suited for a host
of applications in biotechnology and biomedicine.
Last modified 10 July 1998
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