Cutting water droplets down to size.

Chemist George Whitesides and his collaborators at Harvard University have developed a system for making uniform water droplets so small that each one has a volume -[10.sup.11] liter -- approximately equal to the fluid content of a typical biological cell. "No one has ever seen such drops before:' Whitesides says. "When you work on this scale, fundamentally new phenomena show up."

Whitesides anticipates that these tiny water droplets may serve as a starting point for studying the kinds of processes that go on inside cells, without having to worry about the membrane or wall that normally defines a cell's interior. "It's like a grape with the skin peeled off," Whitesides says. "You would have a naked cell." Moreover, these minuscule droplets may have unusual characteristics more typical of materials with large surface areas than bulk materials. They could also be used in microreactors to do chemical analyses of very small quantities of substances, a technique likely to prove helpful in biomedical studies, Whitesides says.