Scientists at the Massachusetts Institute of Technology (MIT) have created a new polymer film that can generate electricity from water vapour.
The new film is made from an interlocking network of two different polymers. One of the polymers, polypyrrole, forms a hard but flexible matrix that provides structural support. The other polymer, polyol-borate, is a soft gel that swells when it absorbs water. The films harvest energy found in the water gradient between dry and water-rich environments.
When the 20-micrometre-thick film lies on a surface that contains even a small amount of moisture, the bottom layer absorbs evaporated water, forcing the film to curl away from the surface. Once the bottom of the film is exposed to air, it quickly releases the moisture, somersaults forward, and starts to curl up again. As this cycle is repeated, the continuous motion converts the chemical energy of the water gradient into mechanical energy.
The MIT states harnessing this continuous motion could drive robotic limbs or generate enough electricity to power wearable electronics.