Harvesting kinetic energy to charge gadgets is nothing new.
We've covered piezoelectric generators that are embedded in sneakers or even
backpacks that charge a battery that can then charge your phone. A new nano
generator developed by researchers at University of Wisconsin, Sun Yat-sen
University in China and the University of Minnesota Duluth could be embedded in
the phone itself or in an outer case so that power harvested from vibrations
like those created by a moving car could be used to instantly charge the phone.
No wires needed.
The researchers describe their device as a mesoporous
piezoelectric nanogenerator. University of Wisconsin explains just what that
means:
The nanogenerator takes advantage of a common piezoelectric
polymer material called polyvinylidene fluoride, or PVDF. Piezoelectric
materials can generate electricity from a mechanical force; conversely, they
also can generate a mechanical strain from an applied electrical field.
Rather than relying on a strain or an electrical field, the
researchers incorporated zinc oxide nanoparticles into a PVDF thin film to
trigger formation of the piezoelectric phase that enables it to harvest
vibration energy. Then, they etched the nanoparticles off the film; the
resulting interconnected pores - called "mesopores" because of their
size - cause the otherwise stiff material to behave somewhat like a sponge.
The sponginess is key. The softer the material is, the more
sensitive it is too small vibrations, the researchers say.
The nanogenerator is made up of the soft mesoporous polymer
film sandwiched between two thin electrode sheets. This flexible film can be
attached to flat or curvy surfaces including human skin, but in this case, the
researchers see it being used in a phone's back panel or housing where it can
automatically harvest energy from vibrations to power the phone directly.
This device has great potential because not only could it
make self-powered phones and sensors possible, but it can also be scaled up to
large manufacturing.
