Kiwi scientists have unveiled wearable technology that can be powered by your own body motion - and it may eventually be possible to self-charge your smartphone.
StretchSense, a University of Auckland spin-out company, has launched an energy harvesting kit that can be used to generate a small amount of electricity while walking.
While not enough to power an MP3 player, it's an adequate amount to feed the company's own soft-sensor technology, which acts like a rubber band with Bluetooth and can record real-time information about the wearer while they run, jump or play video games.
The technology includes a soft generator that, each time it's squashed by a shoe, converts the resulting mechanical energy into high-voltage electrical energy.
This is then harvested and converted to a low-voltage output which can be used to power electronics.
StretchSense chief executive Dr Ben O'Brien said the 1mW of power generated was more than enough to power his company's sensors, along with activity trackers, wireless GPS transmitters or any other low-power microelectronics. The system was activated much like a lawn mower in that it needed a jump-start.
"There's a battery you connect to it to give its first kick and as long as you are supplying continual mechanical energy, it recycles that initial charge to produce a power output."
As the technology improved, he expected much more power could be generated. "For example, when you go out for a run, around 8W of energy is being dissipated as waste heat in your heel strikes.
"So [if you were] capturing 10 per cent of that, you could generate about 1W."
Dr O'Brien thought it would be eventually possible to power larger devices like smartphones.
"The amount of energy you create is proportional to the mass of generated material - but if you want to go to the level of a phone, you might need 100 to 200 times as much generator material as we're using at the moment."
His company's own ultimate goal was to make its sensors self-powering in what would be a new generation of wearable technology called "disappearables".