In the past few years, the promises of biotechnology-new knowledge of health and disease, better diagnostics and treatments-have been driven ever closer to fruition by an unprecedented torrent of biological data flowing from research labs. One of the key technologies generating this critical new wealth of information is a postage-stamp-sized slide of glass or plastic called a DNA microarray or, more colloquially, a DNA chip.

DNA chips made their big splash in 1996 when Santa Clara, Calif.-based Affymetrix introduced the first commercial version, which the company dubbed GeneChip. Affymetrix uses light-sensitive chemical reactions to grow a gridlike pattern of as many as 400,000 short DNA strands, called probes, on a glass wafer. Since each probe can bind to a different gene sequence in a sample of DNA, the chips allow researchers to perform what once would have been thousands of separate experiments all at the same time. Researchers in biotechnology, pharmaceuticals and the Human Genome Project were dazzled by the possibilities: new understanding of the role genes play in heart disease or antibiotic resistance, tools for prenatal or infection diagnosis that incorporate all the genes of interest on a single chip, massive-scale automated screening of potential drugs.