A research team at the Tokyo Institute of Technology has developed a plastic motor that is powered solely and directly by light. Unlike solar-powered motors, which use photovoltaic cells to convert light to electric power and therefore require wires and batteries to deliver and store the power, the light activated motor converts light directly into mechanical energy. The first of its kind motor achieves this by using a belt made from a special elastomer whose molecular structure expands or contracts when illuminated, depending on the wavelength of light.
The team, led by Professor Tomiki Ikeda, began working on the light-activated motor in 2003, after discovering that a plastic compound containing azobenzene would contract when exposed to ultraviolet light and resume its original shape when exposed to visible light. The researchers were able to turn a pair of wheels measuring 10 millimeters and 3 millimeters in diameter by shining ultraviolet light on a 0.08-millimeter thick belt coated with the shape-shifting plastic and looped around the wheels. By shining ultraviolet light on the belt near the smaller wheel and visible light near the larger wheel, the belt snapped into action and began turning the wheels with the 10mm wheel recording a top speed of 1 rpm.
According to the researchers, the film demonstrated about 4 times more elastic strength than human muscle, and its strength remained unchanged even after contracting and expanding every 7 seconds for 30 hours. “The material is still not very efficient at converting light to energy, but it can be improved,” says Ikeda, who hopes to one day see the material used to power plastic cars amongst other things. Thinking like that might just solve the world’s oil crisis – wait, plastic isn’t made from oil is it?
The results of the research were published in the July 19 edition of the German chemistry journal Angewandte Chemie.