By Elizabeth LandauCNN.com
September 22, 2009
Forgot to charge your cell phone last night? Imagine that you could power it by walking. Weirder still, you might be able to just spray a new battery on.
These concepts are being developed by two leading nanotechnology researchers who are developing cleaner, more efficient ways of delivering electrical power. In working toward making these ideas realities, they are making use of structures that are 100 nanometers or smaller, where one nanometer is a billionth of a meter.
"[The nanoscale] can make the components small, sensitive and high-performance," said Zhong Lin "Z.L." Wang, distinguished professor at the Georgia Institute of Technology's College of Engineering. "The toughness and the flexibility increase by orders of magnitude."
Barely lifting a finger
Wang and colleagues are working on harnessing the energy of the body's natural movements to power small devices. Even the simple act of moving your fingers while typing creates energy that could power a small device, and these researchers are showing that nanotechnology can enable this transformation.
Here's the hard science: To take advantage of animal movement for energy, Wang's team makes use of the piezoelectric effect, which refers to the ability of certain materials to generate an electric potential when a stress is applied to them. For instance, if you compress a crystal, it temporarily changes shape, causing the ions inside the crystal to polarize and produce a voltage drop.
That potential can drive a transient flow of external electrons to function as an energy output.
Zinc oxide nanowires, which are environmentally friendly, have this property. Wang and colleagues are using these materials in making solar cells, which would have less potentially harmful impact on the environment than the traditionally-used silicon. They also use them make nanogenerators that can potentially harvest the energy from any mechanical movement.
The group had success in animal models -- for instance, in harvesting energy from a hamster running on a wheel that wears a nanodevice on its back. They have also implanted a nanogenerator on the heart of a mouse, and are able to capture energy from just the heart beat -- albeit only some picowatts (one million millionth of a watt).
[ read full story ]
[ return to table of contents ]