This polymer film is expanding and contracting like a muscle, and looks pretty alive doing it, but the energy is coming from water vapor, not black magic. Go figure.
Researchers at MIT hope to use the material's continuous motion to generate electricity for nanoelectronic devices, like tiny sensors, or as muscles in robots.
The material is made of two interlocking polymers. One lends structure, while the other swells like a sponge as it absorbs water. In a humid environment, water droplets on a surface under the material cause the film to begin curling. As it moves, air dries the film making it stretch and flip, which exposes it to the moist surface again.
Drawing power from humidity is advantageous because water vapor is ubiquitous and relatively easy to control in most environments, at least compared to pH or temperature which have been used in similar experiments.
To generate electricity, the novel film would be combined with a special material that converts the mechanical energy in its movement to electric charge.
It's not a coincidence that the film was developed at MIT's Institute for Integrative Cancer Research. The material, which is very early in development, shows possibilities for biomedical work like targeted drug delivery or physiological monitoring.