Wearable device harvests energy from bending of the knee

As compared to most other joints in the human body, the knee has quite a large range of motion … so why not put that motion to use, as a source of electricity? That's what a new prototype device does, and it reportedly does notcause its wearer to expend more energy while walking.

Developed by scientists at the Chinese University of Hong Kong, the 307-gram (0.7-lb) device incorporates a slider-crank mechanism, which converts the rotary motion of the knee into linear motion.

That mechanism consists of a rod (attached to a band on the wearer's thigh), which moves in and out of a "slider" that's attached to a band on their calf – both units are able to pivot, changing their angle relative to the bands. Therefore, as the user walks, their knee motion causes the rod to move straight in and out of the slider.

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