New material harvests energy from water vapour

The material is made from an interlocking network of two different polymers. One forms a hard but flexible matrix that provides structural support, while the other is a soft gel that swells when it absorbs water. Together these polymers create a material that converts water vapour to energy without the use of an external energy source. When the 20micrometre thick film is exposed to moisture, the bottom layer absorbs the evaporated water, forcing the film to curl away from the surface. Once the bottom of the film is exposed to the air, it quickly releases the moisture, causing it to somersault forward and start to curl up once more. The researchers were surprised to discover that the material not only needs a very small amount of vapour, but that it also demonstrated a large amount of strength. Using only water vapour as an energy source, the film was able to lift a load of silver wires 10 times its own weight. Lead researcher Mingming Ma believes harnessing this continuous motion could drive artificial robotic muscles or generate enough electricity to power small electronic devices.