#34: World’s Smallest Electric Motor

Single-molecule motor is 60,000 times thinner than a human hair.

By Elizabeth SvobodaDec 29, 2011 6:00 AM


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A record-setting electric motor, which debuted last year, pushes superlatives to the limit: It consists of a single molecule, measuring just 1 nanometer across, 1/60,000 the width of a human hair. The motor is about as small as a mechanical device can be, and yet it actually works.

Designed by Tufts University chemist Charles Sykes, the motor runs on energy from a scanning tunneling microscope, which normally reads the shape of a surface by moving a thin metal stylus across it. In this case, the scope’s tip supplies an electric charge to carbon and hydrogen atoms that extend outward and act like a kind of propeller. When struck by electricity, the molecule rotates. One rotating molecule can spin other molecules attached to it, converting electricity into mechanical power, just like larger gears.

The device has made the Guinness World Records, but Sykes hopes it will prove valuable as more than a curiosity. He thinks the motor will eventually pump fluids through minuscule lab-on-a-chip devices that could perform diagnostic tests and turn gears in nanoscale electric circuits that detect chemicals. The motor may also provide insight into the workings of the biomolecular machines that harness energy from food to perform mechanical work such as cell division and muscle movement. “Our motor is akin to these biological systems,” Sykes says. Helping science understand them could be the miniature engine’s mightiest feat.

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