Tiny boat keeps going and going on drops of fuel

Sandrine Ceurstemont, editor, New Scientist TV

If you've ever made a soap boat, you'll know that a few drops of detergent won't propel it for long. But by using an aerogel, Robin Ras from Aalto University in Finland and colleagues have managed to make a mini boat that zips around for much longer.

In this sped-up video, the tiny vessel cruises around for 54 minutes on water powered by just 25 microliters of ethanol. When a few drops of fuel are placed at the back of the boat, vapour diffuses through the aerogel as it evaporates. This lowers the surface tension at the rear, creating a difference in surface tension between the front and back of the boat to propel it forward. The vessel can also travel in oil, as shown in the second clip, since the aerogel is impermeable to oil as well as water.

According to Ras, the system could be useful for transporting small devices across the surface of a liquid. The team found that the speed of the vessel could be altered by using different fuels.

A similar propulsion system is used by water striders when they accidentally fall in water. By excreting a liquid surfactant, they are able to zip to the shore.

If you enjoyed this post, you might like to see how a nanorocket could help deliver drugs or how a mini- machine can move through water by rotating.

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