Researchers Create Spiral Ribbons Converting Light into Macroscopic Motion
17 February 2014
Researchers at the University of Twente's MESA+ research institute have taken up the challenge of intensifying molecular motion and bringing it to the macroscopic world by creating spiral ribbons of molecules containing nanoswitches, which have the ability to transform light into complex macroscopic motion. The research, for which the scientists sought inspiration from the movement in plants, holds promise for the development of soft robotics and microfluidic devices.
The experiment, published in the Nature Chemistry journal, builds upon previous work involving the construction of different molecular machines such as molecular tweezers, scissors and even molecular nanocars, whose motion, however, is generally restricted to the nanoworld. To overcome the limitation, the team led by Nathalie Katsonis created spiral ribbons that curl, twist, contract or expand when exposed to UV light. The spirals can also be used to perform work, for example by shifting magnets.
The spirals are made of thin strips cut from a film of liquid crystal doped with molecular switches, which have a length of several nanometers. When the spiral is illuminated by UV light, the strip contracts on the inside and expands on the outside at the same time, causing the spiral to curl up. The spiral reverts to its previous shape after a certain period of time or when it's exposed to normal light.
The original shape of the strips could be determined by choosing the angle at which they are cut in the film, which allowed the researchers to pick from a right-handed spiral, a left-handed spiral and even a combination of both shapes.