A motor made of a single molecule: electric current sets it spinning by recoil
KIT researchers have built a molecular electric motor with a new drive principle: when current flows through a helical molecule, the recoil of the electrons makes it rotate in one direction.
Archive image · Photo: J. Gundlach, E. Rotzinger / Wikimedia Commons, CC BY-SA 3.0 (cropped and resized)
A team at the Karlsruhe Institute of Technology (KIT) has developed and operated a molecular electric motor that works on a new principle. When current flows through a helical molecule, the recoil of the electrons sets its moving part rotating in one direction – KIT compares this to a garden hose that moves as water flows through it. The results were published in the journal Nature Chemistry, and KIT reported on them on 28 October.
For the experiments, the researchers used a scanning tunnelling microscope to pass current through specially made molecules and observed their response. "The new drive mechanism represents a substantial advance in our understanding of molecular electric motors," says Lukas Gerhard of KIT's Institute for Quantum Materials and Technologies. Unlike earlier approaches, in which the molecule is excited and releases energy to its surroundings, the recoil drive could work more energy-efficiently.
Molecules are suited as electronic components because the strong bonds between their atoms keep them stable even at room temperature – unlike conductive tracks only a few atoms wide. As one possible application, KIT mentions surface coatings that drive specific chemical reactions, though much more research is needed first. Only last week, an international team including the University of Augsburg described a similar principle in Nature: a molecule modelled on the Archimedes' screw that rotates under current and conducts up to a hundred times better than at rest.