Pretty soon, we won't need battery chargers at all

Jan 28, 2015 15:09 GMT  ·  By
Mr. Jinwoo Lee and Prof. Kwang-Seok Yun test the motion energy harvester
2 photos
   Mr. Jinwoo Lee and Prof. Kwang-Seok Yun test the motion energy harvester

Solar power isn't likely to do much for small wearable devices even if we bring efficiency of solar cells from the paltry 11-15% to 50% or 100%. There are other sources though, like the kinetic energy inherent in natural motions.

As it happens, a body motion energy harvester is exactly what researchers at Sogang University in Korea are developing.

The team at Sogang University's Micro & Nano Engineering Laboratory (MNELAB) is to create technologies capable of turning the motions of arm and leg movements into electricity that can power wearable devices, both casual and medical.

The knee, the elbow, the hips and the shoulders are particularly favored targets, as they provide many possibilities for kinetic energy harvesters mounted on flexible substrates.

The ultimate goal is to create clothing, or clothing accessories, that have the necessary flexibility and elasticity to keep up with repeated movements while carrying out their energy conversion task ad infinitum.

The elastic motion energy harvester is not made of elastic

The current design can stretch 1.6 times its normal length, without using actual elastic. Instead, a polymer piezoelectric film is used, shaped along with a fabric strap into a double-helical spring structure with air gaps between the piezoelectric film and the elastic support material.

Bandages, patches, clothing articles, all these things can be designed to incorporate the material, enabling them to harvest not only wide motions but also regular ones and low-frequency natural motions like stretching, bending expansion, etc.

This is actually a pretty big deal, since most motion energy harvesters only work with specific, repetitive motions (it's why footwear-based approaches are popular).

In layman's terms

Based on lab tests, a square patch with a width of 100 mm should be able to produce the power needed by hearing aids, pacemakers, cochlear implants and neurological stimulators. That's several dozen milliwatts.

They could become auxiliary power sources for smartphones, smartwatches, augmented reality headsets and any other device as well.

The time frame

No specific one is given, but we could see the first clothes or patches being put to good use in a matter of years. Meanwhile, the researchers will be analyzing the energy conversion processes more deeply, in the hopes of bringing the energy output from the several dozen milliwatts to hundreds, thus turning the new fabric into the main power source of any electronic you happen to be carrying. Let's hope we won't end up electrocuting ourselves.

The patch shows its worth
The patch shows its worth

Photo Gallery (2 Images)

Mr. Jinwoo Lee and Prof. Kwang-Seok Yun test the motion energy harvester
The patch shows its worth
Open gallery