Scientists shrank Archimedes’ screw to one molecule that can boost conductivity up to 100 times

A spiral-shaped molecule only a few nanometres long has been made to spin when electric current runs through it, and the spinning can raise its own electrical conductivity by up to 100 times. Physicists and chemists in Germany, Israel and Denmark built the device on the pattern of Archimedes’ screw, the water-lifting helix first described more than 2,000 years ago. The work appeared in the journal Nature in October 2026.

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Only two metal contacts touch the rotor. That detail matters because earlier molecular motors typically turned in solution, driven by light or chemistry, and were free-floating. A motor that sits between electrodes, takes its power from the current itself and can be told which way to turn is a different kind of component, one that speaks the native language of electronics. Pauly’s group frames the result as the first electrically driven molecular motor firmly connected to two metal electrodes that turns in a controllable direction, which is the claim the Nature paper rests on.

A helical molecule wired between two gold tips

The molecule was designed in the group of Michael Pittelkow at the University of Copenhagen, and Interesting Engineering describes it as a dithioacetyl-functionalized helicene. According to the University of Augsburg account carried by ScienceDaily, it is a spiral that binds to gold through sulfur atoms. Measurements were run at the Weizmann Institute of Science in Israel, where the group of Oren Tal and Anil Kumar Singh placed single molecules between two gold tips sharpened to atomic dimensions.

By moving the tips closer together or further apart, the team could stretch or squeeze the spiral like a spring. The same family of helical molecules had been studied for that spring-like behaviour in an arXiv preprint from November 2025 listing Singh, Tal, Pittelkow and Augsburg’s Fabian Pauly among its authors. That earlier paper reported that conductance changed in a U-shaped way as the electrodes pulled apart, and it traced the effect to quantum interference inside the molecule.

Electrons as the engine: angular momentum and handedness

Augsburg’s Fabian Pauly said the team had shown that an electric current can generate a directed rotation. In the chemeurope write-up of the Nature study, the mechanism is compared with wind turning a turbine: electrons crossing the helix hand some of their angular momentum to it, and the handedness of the coil sets the direction of travel. Flip the polarity of the voltage and the rotation reverses.

Direction is set by two things only: the handedness of the spiral and the polarity of the applied voltage.

Below a threshold voltage the molecule moves in steps. Above it, the calculations predict continuous rotation. Published summaries of the work do not give the threshold in volts, though the Interesting Engineering report notes that it can be shifted by changing the gap between the gold tips, which is one more reason the stretching experiments mattered. In other words the same mechanical knob that tunes the spring also tunes when the motor starts to run, so a device could in principle be switched on and off by distance alone.

Why rotation opens a 100-fold conductance gain

The 100-fold figure comes from geometry. How easily current passes through the molecule depends on the angle at which it sits between the electrodes. Some angles conduct far better than others, but the molecule rarely settles into those angles when at rest. Rotation sweeps it through them anyway, and across a full turn conductance can climb by up to two orders of magnitude, a factor of roughly 100.

León Martin, who carried out simulations at Augsburg, put it as a matter of access: only the rotation makes the best-conducting positions reachable. His colleague Yuta Ito pointed to why the effect took computing to explain. In the laboratory only the current is visible, so the link between spin and signal had to be reconstructed from quantum mechanical simulations run on Augsburg’s LiCCA supercomputer.

A simplified model built with theory collaborators Per Hedegard of the Niels Bohr Institute and Jing-Tao Lu of Huazhong University of Science and Technology reproduced both the rotation and the jump in current, according to the ScienceDaily summary. Agreement between a minimal model and the full simulation is what gives the authors confidence that the mechanism, rather than a measurement artifact, produces the gain.

What a single-molecule screw could be used for

The authors list molecular electronic components, spintronics and microfluidic systems as possible uses, and they describe the machine as a new tool for studying physical processes at the atomic scale. Pauly called it a new operating principle for machines at the limits of miniaturisation. Funding came from the German Research Foundation, the European Research Council and the Israel Science Foundation, among other national and private foundations, which reflects how many groups were needed to make, measure and model a single spinning molecule.

Caveats remain visible in the coverage. The sources do not state the operating temperature, the speed of rotation or how many cycles a molecule survives before the gold contacts or the sulfur bonds fail, and each measurement involves one molecule at a time held between two tips. Whether thousands could be wired in parallel on a chip, which any practical memory, sensor or switch would need, is not addressed in the coverage, and none of the named researchers is quoted on a timeline for such devices. The peer-reviewed paper, “Current-Driven Molecular Machine with Rotation-Enhanced Conductance”, is the place to look for those numbers.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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