Chip uses less DNA and decodes quicker.

Genetics laboratories nowadays routinely generate DNA "fingerprints." These bar-code-like patterns can help determine paternity or criminal guilt, or provide genetic data for scientific studies.

Conventional analysis requires snipping many copies of a DNA strand into pieces of varying lengths and using electricity to force them through a gel--a process known as electrophoresis. It can take an hour to days for the pieces of DNA to traverse the electrophoretic gel and separate into bands according to their length.

Now, scientists at the California Institute of Technology in Pasadena have demonstrated a new microchip that can make such DNA analyses 100 times faster, while requiring samples of only one-millionth as much genetic material. Channels in the rubbery plastic chip conduct molecules, one by one, past a laser.

The device takes advantage of a method developed earlier this decade to determine the length of DNA fragments tagged with fluorescent dyes. Under laser light, the fragments fluoresce according to their length. Such measurements provide a rapid profile of the sizes of the pieces.

"We've invented a chip-based, single-molecule method for sizing DINA that works on a completely different principle than electrophoresis," says Stephen R. Quake, who led the research team. In the Jan. 5 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, he, Hou-Pu Chou, Charles Spence, and Axel Scherer report fingerprinting a virus' DNA cut into 3,000 pieces--just 28-billionths of a microgram--in 10 minutes.

The device might also speed efforts to decipher the entire set of genetic instructions, or genome, of humans or other organisms, the authors say. In particular, it could accelerate mapping, a preliminary step in the process.