A robotic insect that walks on water like a water strider has helped researchers understand how the bugs propel themselves across the surface of ponds and lakes.



A team of scientists from the Massachusetts Institute of Technology has developed a robotic version of the water strider that captures the essence of the organism’s movement.



The team was trying to test how water striders move across the surface of water, as previous theories incorrectly predicted that young water striders would be too weak to move.


Surface tension explains how striders can stay on the water’s surface without sinking, but only careful experimental study led to an explanation of how they move.



“What we did was to apply some conventional techniques of flow visualization in fluid dynamics,” MIT’s John Bush told BBC News Online.



“You basically sprinkle dye or tiny particles into the water and record what happens with a high-speed camera,” he says.




Bush and his team soon found from video recordings that water striders cause telltale hemispherical vortices when they move.



These suggest that the striders row across the water’s surface without penetrating it.



This insight guided the team to construct a self-contained mechanical water strider that moves in a similar way to its natural counterpart.



The robotic version is much bigger and less graceful, but still captures the essence of the natural phenomenon.

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