To understand disease and develop new drugs, researchers often must begin by sorting the jumble of cell types in a living organism-tumor cells from normal cells, for instance. In some cases, a refrigerator-sized "fluorescence-activated cell sorter," or FACS, can do the job. These machines, however, are expensive ($250,000), tricky to operate and prone to contamination. Now a team at Caltech, led by applied physicist Stephen Quake, has built a "microFACS," reducing the complicated system of pumps, tubes and nozzles to micrometers-wide channels in a stamp-sized rubber chip.

George Whitesides, a Harvard University chemist who developed some of the technology used by the Caltech team says, "Quake brings the perspective of a physicist to this problem in bioanalysis, with results that are, to me, spectacular." Bay Area-based Mycometrix aims to make prototype microFACS systems available to potential customers by year's end; the startup was formed in 1999 to commercialize technologies from Quake's lab. Vice president of business development Todd Krueger estimates that the reader will sell for $40,000, the disposable chips for less than $20 apiece. By making cell sorting cheaper and simpler, he says, the system should open up a host of new applications for the technique outside the lab, including doctor's-office diagnosis and food or water screening.