Instead of specialized laboratories, equipment, and personnel, the DNA testing of the future may be done on a glass and silicon chip smaller than a child's pinkie finger. That's the potential of the tiny "lab-on-a-chip" developed at the University of Michigan, Ann Arbor. Incorporated in simple, low-cost, portable instruments, the chip should produce major benefits in fields as varied as medical diagnostics, forensics, and agriculture, researchers say. Among the potential applications: diagnosis of infectious diseases in minutes rather than days, rapid identification of crime suspects, and on-the-spot categorization of endangered species in remote locations. The chip includes systems for metering, measuring, and mixing microscopic liquid samples of DNA with reagents, moving the mixtures to an integrated temperature controlled reaction chamber, separating DNA molecules by size, and determining the results with an on-board fluorescence detector. All components are contained on a single glass and silicon wafer, except for external light and air-pressure sources and a printed board containing control circuitry. The researchers include Mark A. Burns, David Burke, and Carlos Mastrangelo.