Charge your phone from the vibration of your moving car

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.