Scientists shrink Archimedes’ screw to the size of a single molecule
Scientists have built a groundbreaking molecular motor that spins in either direction using electricity, inspired by a machine invented more than 2,000 years ago. Even more remarkably, its rotation can boost electrical conductivity by up to 100 times, potentially transforming the future of molecular electronics.
Key points
- Scientists built a molecular motor that spins when electric current passes through it and reverses direction when voltage polarity changes.
- The motor uses a spiral molecule inspired by the Archimedes screw, positioned between two atomically sharp gold tips.
- Simulations showed conductivity increased up to 100 times during rotation because highly conductive positions are normally avoided at rest.
Scientists have created a molecular motor that rotates when electricity flows through it and can reverse direction when the voltage is switched. The machine is inspired by the Archimedes screw and represents a step toward working machines at the smallest scale.
The research involved the University of Copenhagen, the Weizmann Institute of Science in Israel and the University of Augsburg. The motor's central component is a spiral molecule a few millionths of a millimeter in size, created by Prof. Michael Pittelkow's group.
How the motor works
Researchers led by Prof. Oren Tal and Dr. Anil Kumar Singh at the Weizmann Institute positioned individual molecules between two gold tips sharpened to atomic dimensions. By changing the separation between the electrodes, they could stretch or compress the molecular screw.
When voltage was applied, the molecule began rotating. Changing the voltage's polarity reversed its direction. Electrons traveling through the spiral molecule transfer angular momentum to it, producing rotation similar to how moving air turns a wind turbine.
The surprising thing is that it is precisely the positions that the molecule avoids when at rest that conduct electricity best. It is only the rotation that makes these positions accessible
— Léon Martin
Surprising electrical effect
The rotating molecule conducted electricity much more efficiently than when stationary. Prof. Dr. Fabian Pauly and his PhD students Léon Martin and Yuta Ito at the University of Augsburg used quantum mechanical simulations on the LiCCA supercomputer to investigate.
Their calculations showed conductivity increased by as much as 100 times during rotation. The positions that conduct electricity best are ones the molecule naturally avoids when at rest, and rotation makes them accessible.
