Bacteria Pump

As microscale devices get smaller and smaller, researchers look for new ways to control movements inside them. A team at the University of Arkansas, led by mechanical engineer Steve Tung and bioengineer Jin-Woo Kim, has developed a way to pump tiny amounts of fluid by harnessing the motions of living cells. Unlike electrical or mechanical systems that rely on high voltages or pressures, the new technique uses harmless bacteria, each of which attaches a leglike appendage to a flat surface and rotates about this anchor point. The rod-shaped bacteria spin “like a merry-go-round,” says Tung, at 10 cycles per second. The trick, he says, is getting the cells to stop, go, or change speed by adjusting their glucose intake. With a few cells lined up in a glass-walled channel, Tung and Kim plan to show that the device can move the 0.25 nanoliters per minute a computer model predicts is possible. Tung says that could lead to biomechanical chips for drug delivery and DNA sequencing in about three years.