Over the years, we've seen a variety of devices that convert the energy in our movements into electricity. The devices could be embedded into shoes, our phones, sidewalks and more. The idea of futuristic, electricity-generating clothing, whether solar powered or human powered, has also been around for a while, but so far the concepts have remained just that -- concepts.
Researchers at Vanderbilt University believe they've developed a breakthrough that will move these ideas from concept to reality. The device harnesses energy from even the smallest human movements like bending or shifting weight and is only a few atoms thick meaning that it can be embedded into fabrics without changing their appearance or feel, far from the far-out clothing concepts we've seen in the past.
The result could be everyday clothing like shirts or jackets that power our personal devices like smartphones, fitness trackers, environmental sensors or medical devices, all from our regular daily activities like walking or even just sitting.
"In the future, I expect that we will all become charging depots for our personal devices by pulling energy directly from our motions and the environment," said Assistant Professor of Mechanical Engineering Cary Pint, who directed the research.
Pint said that this device is novel not just because of its thinness -- the building blocks of the device are an amazing 1/5000th the thickness of a human hair -- but also because of its ability to harvest energy from very slow frequency movements, those lower than 10 Hertz. By comparison, many existing piezoelectric materials, which convert mechanical strain like from the pressure of a footstep into electricity, work best at frequencies over 100 Hertz. That means they only capture energy from a small percentage of human movement and operate about a 5 - 10 percent efficiency.
This new device is made to operate at over 25 percent efficiency thanks to capturing even slow human movements and its able to sustain current generation over the duration of a movement.
The device is far from perfect, however. The team now must focus on increasing the voltage the device produces since it's currently only in the millivolt range, but they're already working on approaches that should boost the output.