A New Nanogenerator

Researchers are experimenting with a novel nanowire material to power tiny biosensors and portable devices.

Using a simple laboratory setup, researchers have shown that barium-titanate nanowires can convert mechanical energy into electricity. The advance could lead to nanogenerators that power tiny biological sensors, nanodevices, and portable electronic devices.
Wireless biosensors that monitor pathogens in water and measure blood pressure or cancer biomarkers in the body are shrinking to nanometer dimensions. To operate them, researchers are looking for equally small power sources. Nanowires that convert mechanical energy into electricity are a promising technology.
Now researchers at the University of Illinois at Urbana-Champaign (UIUC) have taken the first step toward building a nanogenerator out of barium titanate. So far, efforts to make nanogenerators have focused on zinc-oxide nanowires. But barium titanate could lead to better generators because it shows a stronger piezoelectric effect. Lab experiments show that a barium-titanate nanowire can generate 16 times as much electricity as a zinc-oxide nanowire from the same amount of mechanical vibrations, he says.
Nanogenerators could lead to many advances: biomedical sensors powered by blood flow or muscle contractions, tiny gas sensors that run on wind or acoustic waves, pathogen monitors powered by water flow, and portable electronics that are hooked up to nanowires in shoes.

But zinc oxide has its own advantages. It is nontoxic to biological systems, so it might be better suited than barium titanate for implantable devices. Also, it is easier to control zinc-oxide growth in order to fabricate nanowire arrays. "To make an applicable device, you need to have many nanowires with the same orientation in the same location," Xudong Wang says. That could be hard to achieve with barium titanate.

http://www.technologyreview.com/Nanotech/