Researchers in India say they have developed a prototype of an energy-harvesting device from the cocoons of a domesticated species of silk moth. They hope to put the technology to practical use while also tackling waste materials from the silk processing industry.
The researchers found that the cocoon membranes of the mulberry silk moth Bombyx mori contain trace amounts of several elements such as sodium, chlorine, potassium, magnesium, sulphur, calcium and copper; as well as carbon, nitrogen and oxygen.
Wetting the cocoon makes the elements 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 aluminium electrode to the inner surface of a cocoon and a copper electrode to the outer surface, and exposed the cocoon to water vapour. Three such cocoons were connected in series to light an LED.
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