As a teenager in a rural village in Nepal, Milan Karki knows just how desperately developing countries need an affordable, renewable energy source. But rather than whine about the availability of electricity or the cost of batteries, he sat down and came up with a solution: Low-cost solar panels with human hair conductors.

Solar energy isn't anything new, but solar panels themselves can be pricey to produce due to using silicon. Karki solved the cost issue by using human hair instead since it turns out that Melanin, a color pigment in hair, is a good conductor. Oh, and did we mention that it's cheaper than silicon?

Half a kilo of hair can be bought for only 16p in Nepal and lasts a few months, whereas a pack of batteries would cost 50p and last a few nights.

I don't know why they're selling hair by the kilo, but this idea is absolutely brilliant and I can't wait to see if it turns into something widely used. [Daily Mail]

Now, this is done on a plucked hair by steering a beam of gallium ions over the surface to etch the 20-micron logo into the hair cells. But imagine you really could have your hair tattooed. No-one would see it, it would be just like painting the pilot inside a plastic airplane model: you'd know it was there. What would you have?

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