Harvesting energy from knee

A group of American Institute of Physics researchers has developed a way to power small devices by walking.An energy harvester, attached to the wearer's knee, generates 1.6 microwatts of power while the wearer walks without any increase in effort. The energy is enough to power small electronics such as health monitoring equipment and GPS devices. 

The researchers used a special smart macrofibre material, which generates energy from any sort of bending it experiences, to create a slider-crank mechanism - similar to what drives a motor. The authors chose to attach the device to the knee due to the knee joint's large range of motion, compared to most other human joints. These harvesters can harvest energy directly from large deformations.

Due to the continuous back-and-forth motion the material will encounter when the wearer walks, every time the knee flexes, the device bends and generates electricity. This means the harvester can capture biomechanical energy through the natural motion of the human knee.This energy harvester could promote the development of self-powered wearable devices.