This Gadget Charges Electronic Devices While User Bends Knee

A team of scientists have developed a wearable gadget that can be used to charge electronic devices -- simply by walking.

A team of scientists from the Chinese University of Hong Kong created a lightweight knee brace that could extract energy from its wearer’s knee movements. The 307-gram wearable device, described in research published in the Applied Physics Letters journal, uses a slider-crank mechanism that converts the knee’s rotary motion into linear motion.

According to New Atlas, The mechanism consists of a rod attached to a band on the wearer’s thigh and a slider attached to a band on the wearer’s calf. Both the rod and the slider are able to pivot, and when the wearer walks or bends the knee, the rod moves in and out the slider.

A strip of carbon fiber is attached to the tip of the rod, and adhered on the strip is a “smart macrofiber composite (MFC) material. This material produces an electrical current as it bends. Every time the rod enters the slider, the carbon fiber and MFC material bends, resulting in the production of electrical currents.

How much power can it generate?

According to the scientists, the material produces 1.6 microwatts of power at walking speeds of 2 to 6.5 kilometers per hour.

This amount of energy, the scientists noted (via EurekAlert), will be enough to provide power to small electronic devices such as health monitoring equipment as well as GPS devices.

Wei-Hsin Liao, professor in the department of mechanical and automation engineering and an author in the research, said this will be very helpful to people who go to the mountains where there are no places to charge their GPS devices’ batteries.

"Self-powered GPS devices will attract the attention of climbers and mountaineers," Liao said.

Does it require a certain level of physical fitness?

The scientists also checked if the device has an effect on the wearer’s physical condition when using the device, and compared the wearer’s breathing patterns when the device is worn and when it isn’t worn. The scientists found that it didn’t affect the wearer’s breathing, indicating that it doesn’t require additional effort on the part of the wearer.

"Self-powered equipment can enable users to get rid of the inconvenient daily charge," Liao said. "This energy harvester would promote the development of self-powered wearable devices."