![\"nanohelices\"](\"http:\/\/arxivblog.com\/wp-content\/uploads\/2009\/01\/nanohelices.jpg\" "\\"nanohelices\\"")
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Antennae are the most fundamental energy harvesting devices that we know, says Sung Nae Cho at the Samsung Advanced Institute of Technology in south Korea. So why aren’t they more widely used?<\/p>\n
Turns out that helical antennae are already used to harvest energy and most of us probably own one already in the form of a transformers. These contain a helical winding that rectifies\u00a0 AC into DC.<\/p>\n
Cho points out that it has recently become possible to build nanohelices and that these might also be used for rectification. He’s designed a device that rectifies, not current, but electromagnetic waves. It consists of a nanohelix layer, a diode\u00a0 layer and a capacitor layer, all the components of a standard rectifying circuit.<\/p>\n
The nanohelix layer consists of an array of\u00a0 100 million “pixels” which each contain a single nanohelix. That makes the array no bigger than the imaging chips in digital cameras . Cho calculates that if only 10 per cent of the nanohelices harvest energy from ambient electromagnetic waves to the tune of 130 nA, then the device would produce 1.3A.<\/p>\n
If he’s right, that’s a handy amount by any standards. Anybody volunteer to prove him right.<\/p>\n