Wearing a big, heavy backpack can get pretty tiring. That's why scientists have developed a pack that's not only claimed to lighten the load on the wearer, but that also uses the motion of that load to generate electricity.
Although developed by a team at China's Tsinghua University, the experimental backpack is in fact quite similar to the HoverGlide model that was the result of research conducted at the University of Pennsylvania.
That backpack incorporates a main cargo-carrying pack which is suspended by bungee cords on a pulley system, and that is also mounted on a frame that's worn on the user's back. As that person walks, the pack moves up and down along the frame, but it does so exactly out of step with the user. This means that the pack hovers at more or less the same height while its wearer walks, so they don't need to expend as much energy to move it up and down along with their body.
The Tsinghua backpack works more or less the same way, with a main section that slides up and down rails while suspended by two elastomer cords. This setup is claimed to reduce vertical oscillation of the load by 28.75 percent, which results in a 21.08-percent reduction of vertical force on the wearer.
Additionally, though, the backpack incorporates a triboelectric nanogenerator that converts the energy of the pack sliding along the rails into electricity. It's able to do so with an efficiency of 14 percent under normal walking conditions – that might not sound like much, but it's reportedly enough to power an electric watch, LEDs and a fluorescent tube.
A commercial version of the backpack could also charge up an integrated battery, which might be a more practical application of the technology. The scientists say that such a setup could be useful for athletes, explorers and rescue personnel who walk into remote areas where there's no access to electricity.
And this isn't actually the first electricity-generating backpack we've seen. The Go Kin did so too, although it incorporated reeled cables that ran from the back of the wearer's shoes to a generator in the bottom of the pack. As those cables were pulled in and out by the user's walking motion, the generator was spun up. The product did not reach its Kickstarter goal, however.
A paper on the Tsinghua backpack was recently published in the journal ACS Nano.
Source: American Chemical Society
