A breakthrough in nanotechnology means it may soon be possible to harvest electrical energy from the vibrations caused by a human voice--just enough to add some charge to your cell phone. The trick is for it to work really well, you'll have to actually shout. Which certainly adds a new annoyance to the cell phone use list (just below that guy on the phone while paying for his Starbucks right ... now.)
Energy recovery systems are becoming more and more useful every day--they're a way for quotidien activities to also generate useful amounts of electricity, which has the benefit of being largely carbon neutral and thus a pretty green way to create new sources of power. You already discovered this tech when you encountered exercise bikes in gyms aren't hooked up to the grid. And in Japan, special energy-harvesting platforms are actually used in some train stations to power the ticket machines via the energy of stomping commuter shoes. The difficulty is that on a very small scale, it's hard to collect enough energy from the actions of a human body for it to be useful enough to even bother harvesting in the first place. The tech is advancing though, propelled often by nanotech developments: Like this new one from Sungkyunkwan University in Seoul.
The team of scientists have been looking at the properties of nano-scale strands of zinc oxide (a relatively inexpensive source material) and have worked out how to trap them between two flexible electrodes. When an incoming sound wave hits the flat top pad of the device, it acts to compress and then release the zinc nanowires inside. Thanks to the odd electrical properties of the wires, this action actually generates a tiny electrical current.
In prototype form, the device was able to create a voltage of about 50 millivolts from sound at 100 decibels (think very noisy traffic, or a passing jet aircraft)--far from the 5 to 12 volts at around 500 milliamps needed to actually charge many of our mobile devices today. But with improvements, the team is confident it can up the electrical efficiency of the design so that your voice may be enough to generate a trickle charge to keep your cell phone battery topped-up (or at least enough to keep it running a little longer). Plus such a system wouldn't necessarily need to capture energy just from your voice--background noise would work just as well, as would perhaps the bangs and shuffling sounds of the inside of a pocket or purse, a situation where alternative energy generation like solar cells doesn't work.
In terms of medical devices, implantable sensors or drug delivery systems could easily use a nanotech solution like this, which harnesses the whooshes and gurgles of your body and comes with the added benefit that they'll work in the dark, in the warm, in the cold--basically anywhere you go.
The cynic in us also suggests it may be worth installing huge panels of this nanotech power device in the walls of government debating chambers: At least all that hot air would go to good use!
[Image: Flickr user torimbc]