Researchers Create Device to Harvest Energy From Human Knee

Researchers at the Chinese University of Hong Kong have just developed a device that could harvest energy from the knee to generate electricity.

From visible backpack to the more hidden nanotubes, recent researches have focused on power-generating wearables. This new energy harvester is no different.

After attaching it to the knee, the user has to walk to generate as much as 1.6 microwatts of power. That’s enough to power health monitoring equipment or even a GPS device.

In a statement, author of the study and professor in the department of mechanical and automation engineering, Wei-Hsin Liao said:

“Self-powered GPS devices will attract the attention of climbers and mountaineers.”

Here’s how the device harvests energy from human movement.

How the Knee Device Harvest Energy

Using a smart macro-fiber material, the researchers created a slider-crank mechanism.

Since the material generates energy from any bending, the researchers chose to attach it to the knee joint. That way, the device could harness the range of motions in this body part in generating more energy.

According to Liao, the energy harvester captures biomechanics energy through the natural motion of the knee. That means every time the knee flexes in a continuous back-and-forth movement, the device bends and generates electricity.

While previous wearables have been able to harvest energy from the vibrations that result from motion, they’ve never been efficient.

Liao noted:

“The frequency of human walking is quite slow, which significantly decreases the energy-harvesting capability.”

Since the device depends on actual knee flexes, wearers won’t experience this limitation.

Comfortable Power-Generating Wearable

Participants of the study had to wear the 0.68 pounds prototype while walking at a speed of 1 to 4 miles per hour. Then, the researchers compared the wearer’s breathing pattern with and without the device.

The energy required to walk remained the same in both instances. In other words, the device is generating power at no cost to the wearer.

With such an efficient wearable energy harvester, the idea of self-powered wearables is not so far-fetched.

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

The researchers intend to commercialize the technology soon.