How evaporation is used to power tiny engines

Harnessing the power from a fundamental process that's happening constantly, all over the world, a team of scientists at Columbia University have devised tiny engines powered by evaporation. The devices generate electricity from the energy produced by bacterial spores known as Bacillus subtilis, which exhibit strong mechanical responses to changing relative humidity.

The spores expand when they absorb water and contract when they dry out. By controlling the moisture in the air, produced by evaporation, that the spores are exposed to, the devices grab the energy of these expansions and contractions to drive rotary or piston engines. The research was published on Tuesday in the journal Nature Communications. Read more...