Professor Tomiki Ikeda of Japan's Tokyo Institute of Technology has been working on light-activated motors since 2003, and it looks like his research is yielding some amazing results. The research team has completed a plastic motor, powered only by ultraviolet and visible light. It's not solar energy, though — rather than store up energy converted from light, at the heart of the motor is a shape-shifting elastic polymer, or elastomer. The elastomer changes shape depending on the wavelength of the light it's exposed to: it contracts in ultraviolet light, and expands back to its original size with visible light.
The way the team used this technology to power a motor is pretty genius. They made a belt of the of shape-shifting plastic and wrapped it around two wheels, one smaller than the other. Then they exposed the part of the belt wrapped around the smaller wheel to ultraviolet light and the larger to visible light, and the forces at work sent the belt spinning into motion.
Right now, the technology isn't where it needs to be to power vehicles and the like, but the elastomer shows great promise. It's proven to have four times the elastic strength of human muscle (cyborgs, ahoy!) and retained its shape without warping even after running every seven seconds for thirty hours.
Via Pink Tentacle