Image by Armin Kübelbeck (http://commons.wikimedia.org/wiki/File:E-Paper_01.jpg)
E-book readers are gaining popularity thanks to their capacity and potential for interactivity. Some people still prefer paper books for a variety of reasons, including the fact that they don’t require power. Engineers at Disney Research and Carnegie Mellon University hope that they can merge the best of both technologies with their energy harvesting “Paper Generators.”
Triboelectric Effect
Instead of using batteries to power an e-reader, the Paper Generators create electricity from human motion - touching, tapping, and swiping - combined with energy-harvesting structures. The generators are made from inexpensive materials such as paper and Teflon, and operate on the triboelectric effect - the same principle that causes static electricity when you rub a balloon on your hair. Imagine that - static electricity is useful for something besides shocking your brother when he’s not expecting it!
Materials have certain triboelectric properties related to how easily atoms will give up or acquire valence electrons. Some materials are very likely to give up electrons while others are very likely to accept electrons. Paper makes a good electron donor while Teflon is an excellent receptor. Placing a sheet of Teflon near a sheet of paper creates a triboelectric “battery” that generates a small amount of power when pressed and released, just like the static electricity that’s generated when you walk over a carpet while wearing wool socks. Pressing the materials together causes an exchange of electrons. After the materials are separated, the excess electrons stay on one side, creating a difference in potential (i.e., a voltage) between the two materials.
Use the Energy Now or Accumulate it for Later
Harvesting the electricity involves either using the energy as it’s generated or allowing it to charge a capacitor. The latter occurs when an application requires energy levels higher than those generated by the immediate gesture, such as driving a piezoelectric buzzer. E-paper, on the other hand, requires very little power to operate. It only uses electricity to change the image on the paper; maintaining an image requires no power. That works out nicely, since an E-book display only changes when you turn the page and that can be done by swiping a finger across the display.
Interactive Books
In addition to giving us E-book readers that don’t require batteries, the engineers behind this technology suggest that it can also make books interactive by providing lights and sounds in response to user inputs. They also envision E-books that can send low-power wireless signals to a computer, creating interactive storytelling environments. The inventors describe applications for interactive children’s books - not surprising, since Disney Research is one of the creators.
It Has Potential
This technology looks good on paper, if you’ll excuse the pun, but in practice I’d like to see E-books with the ability to show animations like a computer screen or a tablet does, and that requires more power than a little swipe or tap can generate. I suppose you can tell the reader to swipe her finger back and forth in order to see the animation but that’s still a limitation of Paper Generators. Nonetheless, I can see this idea eventually filling a particular niche market. What’s even more interesting to me is the possibility of spin-off technology. Can the triboelectric effect be used in other energy harvesting applications? What are they?
Click the read more… link to see the detailed description of Paper Generators. Also, check out the video below. At the moment it’s still in the R&D stage. No word yet on when it may be commercially available.