Power joint

Power walking could take on a new meaning now Michigan University researchers have developed a knee brace that generates electricity.

Working like regenerative braking found in some hybrid vehicles, the device harvests the energy lost when a human ‘brakes’ the knee after swinging the leg forward a step.

Researchers believe that device could generate enough power to operate a portable GPS locator, a cell phone, a motorised prosthetic joint or an implanted neurotransmitter.

‘There is power to be harvested from various places in the body, and you can use that to generate electricity,’ said Arthur Kuo, associate professor of mechanical engineering at Michigan University. ‘The knee is probably the best place.’

Tests have revealed less than one watt of extra metabolic power was needed to generate one watt of electricity.

‘We’ve demonstrated proof of concept,’ added Kuo. ‘ But the prototype device is bulky and heavy, and it does affect the wearer just to carry it. The energy generation part itself has very little effect on the wearer, whether it is turned on or not. We hope to improve the device so that it is easier to carry, and to retain the energy-harvesting capabilities.’

The team believe a lighter version of the device would be helpful to hikers or soldiers who don’t have easy access to electricity and similar devices could be built into prosthetic knees or other implantable devices such as pacemakers or neurotransmitters that currently require a battery.

Photo: Greg Ehlers/Simon Fraser University