Monday, January 02, 2006

"NANOTECH: Nanocircuits self-build from DNA"

Just as a poem is composed from a toolbox of 26 characters or a fugue from a 12-tone scale, molecular-scale chips will one day be built from the four-letter alphabet of DNA, a Duke University EE professor believes. To prove the point, Chris Dwyer and his collaborator, Duke professor Thom LaBean, recently demonstrated how to pattern 100 trillion 16-cell (4 x 4) programmable arrays with 2- to 10-nanometer features — compared with 65-nm features today — using just $40 worth of commercially available dioxyribonucleic acid. The 4 x 4 grids in the demonstration were programmed to spell out "DNA," but the researchers claim that eventually an entire memory bit cell could be programmed into larger versions of the grids. Once the grids are populated with the necessary components to form programmable bit cells, they could be deposited on silicon substrates as thin films, or they could potentially be left in the solution in which they were programmed and then addressed with a scanning laser. The circuitry realized on the grids could have optical qualities too. For instance, the circuits might yield liquid-crystal displays with floating pixels that could be toggled to the correct color, depending on where the pixels happened to be floating at any particular moment. Each of the 16 tiles comprised nine coded strands of DNA, obtained from a DNA sample that the researchers had purchased commercially. By performing various wet-chemistry steps in the lab — because DNA can be damaged by direct exposure to air — the researchers were able to coax the floating DNA strands to self-assemble into the grids of 16 tiles, each coded for attaching an electronic nanoparticle, an optical molecule or a nanowire connection.