CHEMISTRY MICROCHIPS might be to chemistry what integrated circuits have been to electronics---a way of rapidly carrying out a myriad of transactions in a compact, controlled environment. Drawing on transistor design principles, early versions of the chemistry chips use voltage (biology has long been able to sort charged molecules by size by pulling them through filters) and gates (based on surface tension) to steer fluid nanoblobs through circuits of capillaries. Applications of the chips include the human genome project and combinatorial chemistry for drug design. (Science News, 15 August 1998.)