Researchers unveil device that harvests energy from human knees

Researchers at a trio of UK universities have found a way to generate energy using only normal human kinetics. Every time you take a step, your knee flexes and bends, and while this does offer a pretty useful form of locomotion, the team of researchers felt that this action wasn’t as perfectly efficient as it could be. Too much theoretical energy was being lost in that bending motion. Thus, they created a machine to fix this glaring flaw of biology.

Officially dubbed the “pizzicato knee-joint energy harvester,” the wearable device gathers and stores energy generated by the bending motion every human knee goes through while walking. Gizmag details the gadget’s specifics:

Known as the pizzicato knee-joint energy harvester, the device fits onto the outside of the knee. It is circular, and consists of a central hub equipped with four protruding arms, surrounded by an outer ring bearing 72 plectra (a plectrum is a plucking tool, such as a guitar pick). The ring rotates about a quarter of a turn with every bend of the knee, causing the plectra to pluck the arms. This causes the arms to vibrate (not unlike a guitar string), and it’s those vibrations that are used to generate electrical energy.

As for the “why” behind this invention, as we mentioned above, the researchers hoped to capture the lost potential energy of the human gait and instead convert this otherwise wasted effort into useful electric energy for devices like heart-rate monitors and pedometers. That said, there’s no reason why this thing couldn’t provide electricity to any gadget you might own. Though the research teams hope the pizzicato will be useful in providing enhanced mobility to people who rely on electronics to survive, it seems quite likely that there might be even more valuable consumer applications for a device that allows a person to recharge their iPhone by taking a walk down the block. Doubly so given that Dr. Michele Pozzi, a lead author on the project, estimates that the final production model of the machine will only cost about $15.

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