News Physics

Tiny particles propel themselves upstream

Environment-sensing microbeads may one day deliver medicines

human-made particle

AGAINST THE FLOW  In a new experiment, micrometer-sized particles sensed their direction and propelled themselves upstream. Each particle (one shown in this micrograph) was made of a plastic sphere engulfing a hematite cube (colored red). 

Stefano Sacanna

By Ashley Yeager

- More than 2 years ago

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Human-made microbeads don’t always go with the flow.

Under certain conditions, the artificial particles can align themselves with a fluid’s flow and then swim upstream, researchers report May 1 in Science Advances.