SSS 2008-11-18（在线收听）

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

In theory, scientists could learn a lot about our health by testing tiny amounts of bodily fluids—a drop of blood, a tear, a bead of sweat. But something this small is easily contaminated by other liquids or surfaces. So what are scientists doing? They're making liquids bounce, dance, and float lightly through the air. Researchers from Belgium's University of Liege published their findings November 18th in the New Journal of Physics.

Usually droplets on a surface of oil eventually just collapse. Something called acoustic levitation was introduced a few years ago, but it takes a lot of complex equipment. Then one researcher noticed something strange. Certain bass notes booming from his iPod could make droplets dance and roll around. He and his colleagues pursued this line of inquiry.

They figured out the appropriate vibrations that make the droplets lightly bounce. This keeps them separate from the oily layer underneath. The result looks as if the drops are rolling around. And the drops haven't had a chance to mix with the fluid below. Researchers say the technique could be used to manipulate tiny amounts of fluid without contamination. Yet another reason why iPods are essential pieces of lab equipment.

Thanks for the minute for Scientific American's 60-Second Science. I'm Cynthia Graber.