Wednesday, May 24, 2006

US Patent 7048889 - Liquid Transport Using Nanoposts

Microfluidic devices typically employ the transport of picoliter (very small) quantities of biological or chemical fluids using electrostatic forces through channels of micrometer dimensions. These devices may be used as biological or chemical sensors by directing the fluid to a reagent that reacts to a particular biological of chemical fluid and provide an indication of the presence of the particular fluid or may be used in a plurality of other "lab-on-a-chip" applications involving fluid mixing, sorting, etc. However, typical microfluidic devices are limited by the necessity of the micrometer sized channels that limit flexibility if more than one reagent is used or more than a single path for the fluid drops under analysis is desired.

The inventors of this patent solve this problem in a novel way by providing a surface with an array of nanoscale posts above which drops of the target fluid may be directed using electrostatic or capillary force. At certain regions at the bottom of the nanoscale posts reagents are placed. The fluid can move freely over the surface of the nanoposts without reacting with the reagents until a mechanism is actuated (for example a heat source may be used to reduce surface tension of the fluid) and the fluid then flows through the nanoposts contacting the reagent. Claim 1 reads

1. A detector comprising: a surface having a plurality of nanostructured projections disposed thereon, the projections having tips; a reagent pixel on the surface, between the plurality of projections; means for moving a liquid across tips of the nanostructured projections without contacting the reagent pixel; and means for moving the liquid toward said surface in a way such that the liquid contacts said reagent pixel.