Scientists Create A Device That Can Generate Power From The Human Knee

A new invention offers a peek of the potential future when just walking could be enough to generate energy for humans' basic and portable devices. The new technology, which was developed by researchers at the Chinese University of Hong Kong, opens up the possibility of greater convenience and efficiency.

In a new paper published in the journal Applied Physics Letters, the team revealed that the technology involved attaching an energy harvester to the knee. From the motions of the wearer walking during the day, the device is capable of generating as much as 1.6 microwatts of power. This amount of energy is enough to power small electronics such as GPS devices and health monitoring equipment.

The researchers developed the energy harvester by creating a slider-crank mechanism with a special smart macrofiber material that produces energy when it bends. Since the knee joints are capable of a wider range of motion than most of the other human joints. Every time the wearer walks and the knee flexes, the device bends and generates electricity. It allows the harvester to capture biomechanical energy from the body's natural motions.

"These harvesters can harvest energy directly from large deformations," study author Wei-Hsin Liao explained in a news release.

Light and handy, the new energy harvester only weighs 0.68 pounds (307 grams), and it was tested on people walking 1 to 4 miles per hour (2 to 6.5 kilometers per hour).

Findings showed that the human subjects exerted no additional effort with the device, which means that the device is producing power at no cost. Low-cost, efficient, and convenient, the new wearable energy harvester has immense potential, and the researchers are planning to explore future commercialization of the technology.

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

He predicted self-powered GPS devices to be popular among climbers and mountaineers, who carry these portable equipment to places with limited access to electricity and charging stations.

There have been previous attempts at wearable energy harvesters, but many focused on the vibration caused by movement. However, Liao explained that the frequency of human walking is slow, which means the capability of harvesting energy is quite limited. Since the new wearable employs a different method, it doesn't have this particular limitation.