Utilizing Nanowires to Generate Electricity

Researchers are experimenting with a new type of nanowire materials to power tiny biosensors and portable devices, since wireless biosensors that monitor pathogens in water and measure blood pressure or cancer biomarkers in the body are shrinking to nanometer dimensions.

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, says mechanical-science and engineering professor Min-Feng Yu, who is leading the research at UIUC. 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. "The nanogenerator idea has become more and more convincing, " says Yi Cui, materials-science and engineering professor at Stanford University. "It's an idea that might work."

In 2006, a team of researchers led by Zhong Lin Wang of the Georgia Institute of Technology first showed that zinc-oxide nanowires could harvest mechanical energy to generate electricity. Wang's group has since made a lot of progress, most recently demonstrating a zinc-oxide nanowire array that outputs direct current in response to ultrasonic vibrations.