Charging your mobile phone could be done just by waving your arms and legs about a bit, according to scientists in the US. Zhong Lin Wang and colleagues have used millions of nanowires made from zinc oxide to generate electric currents from simple body movements, such as walking or even the flow of blood around your body. And the researchers say this technology could negate the need for batteries in the future.
Presented at the American Chemical Society meeting this week, Wang described how these nanowires are piezo-electric, which means every time they are subjected to mechanical stress they produce a current.
Now, last year the researchers placed a nanowire generator in a bio-fluid, passed ultrasonic waves through it and the movement produced a small, but detectable direct current. This time the researchers say that making the nanowires out of zinc oxide means they can generate electricity from much lower-frequency movements. And that includes waving your arms about or the effects of a soft breeze on a fabric. The nanogenerators are made by growing these zinc oxide wires radially around conductive fibres.
They say they do need quite a lot of these nanogenerators to make enough current to run something like a mobile phone. But, the zinc oxide nanowires can actually be grown on all sorts of different surfaces such as metals, ceramics or even clothing. And the wires are only 1/25th the diameter of a human hair so theoretically you could incorporate them into a t-shirt - and they'd remain virtually invisible.
What's even more exciting is that these energy materials generate current in air and in water so, as long as the device you want to charge is waterproof, you can give it some juice while you're swimming.