5 more tech breakthroughs: Innovations in access, power and control

Nanogenerators, self-healing batteries and brain-computing interfaces may sound like science fiction, but they're not.

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Self-powered electronics: Power without the plug

Zhong Lin Wang dreams of electronic devices that can power themselves. If the materials science professor at the Georgia Institute of Technology's Nanoscience Research Group has his way, replacing or recharging batteries could soon seem "so 2010."

ZnO fiber array
A ZnO fiber array.

Wang's team at Georgia Tech has designed tiny generators that can produce enough energy to power very small devices. These high-output nanogenerators, HONGs for short, can produce between 2 and 10 volts from a flexible chip smaller than a fingernail.

The design starts with a microscopic array of zinc oxide (ZnO) fibers, or nanowires, each thinner than a human hair. These fiber arrays are embedded into multiple layers of metal electrodes and plastic polymers to create a flexible nanowire "sandwich."

Under an electron microscope, the strands look like the bristles of a very small brush, and they have the seemingly magical piezoelectric property of producing a tiny electrical current when moved or squeezed. Put billions of them together, and you get enough energy to power devices without using an external source of electricity.

"We turn motion into power," says Wang. So far, HONG devices have lit LED lights, run calculator LCD screens and powered rudimentary electronics in the lab. That's just the beginning.

Wang and his team are working on creating HONGs that can power complete wireless devices. Their current project is to make self-powered environmental sensors for a variety of uses.

For instance, the Georgia Tech team is working on a sensor that could be embedded in a bridge. "Surrounded by concrete, it wouldn't be easy to change the sensor's batteries," Wang quips. But with a HONG generator inside, the sensor could be powered by the vibrations of cars and trucks driving over the bridge.

Zhong Lin Wang
Georgia Tech's Zhong Lin Wang: "We turn motion into power."

The idea is that every 30 minutes, the sensor -- and dozens like it in the structure -- would send a reading to a receiving station for analysis. If the sensors showed that the bridge was in danger of collapsing, the structure could be shut down, preventing a disaster like the 2007 collapse of the Mississippi River Bridge in Minneapolis.

"This is an especially promising area," says NIST's Seiler. "It lets us think less about the device's battery running out of power and concentrate on what it's supposed to do."

While it's unlikely that nanogenerators will ever generate enough power to support large electronic devices like computers or TVs, a plethora of small devices could eventually be solely or partially powered by HONG chips. By 2013, Wang sees self-powered phones, digital music players and even a wireless keyboard powered by nothing more than the musician's keystrokes.

Wang says that the cost of adding a nanogenerator to devices would be low, because zinc oxide is a common material and HONGs are made with current semiconductor processing technology -- although some evolution of processing techniques will be needed. Additionally, HONG chips could lower the cost of certain products by partially or totally doing away with the need for a battery -- one of the most expensive components of any phone or music player.

HONG chip powers a calculator's display
A HONG chip powers a calculator's display.

Members of Wang's research group are also experimenting with more exotic, and potentially higher-power, piezoelectric compounds such as lead zirconate titanate, but they might be harder to process.

The bottom line is that for many of the electronic devices that surround us, the tyranny of the AC outlet and charger may end. "Motion is everywhere, waiting to be used for powering our future," says Wang. "All we need to do is harness it."

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