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.
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.
The idea sprang from research into the mechanical properties of the subtilis spores, which can exist in a dormant state for hundreds of years, being conducted by a Columbia microbiologist. “It struck me as amazing how much mechanical energy they seem to have,” says Ozgur Sahin, an associate professor of biological sciences at the university. “They are so rigid that as the material’s shape changes it produces a lot of energy.”
“We made lot of compromises in creating this version in hopes of creating a self-sufficient device,” he says. “We know actually that it can be made 100 times more powerful by solving number of problems.” Read more…