Knee-powered energy-harvester keeps devices running

Described by the team in Applied Physics Letters, the energy harvester is attached to the wearer's knee and can generate 1.6 microwatts of power while the wearer walks without any increase in effort. The energy is enough to power devices like health monitoring equipment and GPS devices.

"Self-powered GPS devices will attract the attention of climbers and mountaineers," said author Wei-Hsin Liao, a professor in the department of mechanical and automation engineering.

The researchers are said to have used a special smart macrofibre material, which generates energy from any sort of bending it experiences, to create a slider-crank mechanism. 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," Liao said in a statement.

Due to the continuous back-and-forth 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," said Liao.