Scientists in India have found a way to not only harvest the trace amounts of minerals found on silk moth cocoons, but according to a scientific report published by them earlier this month, they have found a way to generate enough electricity using these minerals plus some water to power electronics. From Inhabitat:
Wetting the cocoon makes the trace elements in a silk moth cocoon form mobile charge-carrying ions, producing an electric current across the cocoon membrane. The researchers used this current to light an LED. They attached an aluminum electrode to the inner surface of a cocoon and a copper electrode to the outer surface, and exposed the cocoon to water vapor. Three such cocoons were connected in series to light an LED. The researchers also charged a moist silk cocoon with a direct current source to see if it was capable of acting as a capacitor — a device that stores charge. The study shows that it could power an LED for two to three minutes after the direct current was removed.