The molecular motor works like an Archimedes turbine pictured here. Credit: Pesymista, Wikimedia Commons CC Attribution-Share Alike 3.0Archimedes turbine
Scientists have built a microscopic motor out of a single molecule that rotates like an ancient water pump with electricity1. The machine is made from a screw-shaped helicene molecule and acts like a microscopic Archimedean screw, a tool used for thousands of years to pump water.
Physicists, including Anil Kumar singh at the Indian Institute of Technology Madras, suspended a tiny helicene molecule between two electrical probes. When they applied voltage, the molecule started to spin with 100% perfect directionality. When they flipped the positive and negative sides, it reversed and spinned the other way.
Once the voltage hit a 'tipping point', the molecule started spinning in a smooth, continuous circle, twisting into shapes that allow significantly more electricity to flow through it. As it is a tiny spring, the researchers could physically stretch or compress the molecule to change the exact voltage needed to trigger the power boost.
They provide a prototype for a predictable mechanical torque at the atomic scale.
