Changing Gears

For thousands of years, humans have used cogwheels and gears to turn everything from mill stones to clock hands to engines. But this new design – pushed around by light – churns microscopic particles as a prototype for a new kind of micromotor. The tiny gear (around 10,000 times smaller than a revolving door) is cut out of a polymer and placed on top of a photo-reactive material. A blast of light from above – using a device called optoelectronic tweezers – generates a force at the material’s surface. By rotating this light pattern – researchers call it a 'spanner' (shown in white) – the gear inside swooshes a swarm of particles along. Linked together into systems, micromotors have a bright future inside microfluidic devices, where clues to the behaviour of chemical currents around living cells may depend on their tiny revolutions.

Written by John Ankers

John Ankers

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A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video from work by Shuailong Zhang and colleagues
• Department of Chemistry, University of Toronto, Toronto, ON, Canada
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Nature Communications, September 2021