Water striders have a unique ability to stride across the water. They can also leap upward into the air to escape predators like fish and frogs. An international team of researchers led by Kyu Jin Cho of South Korea’s Seoul National University (SNU) has developed a tiny robot that can skate across the water surface and jump in the same way as a water strider.
How does the water strider accomplishes the jump?
The robot mimics the mechanics of the bug. Kyu Jin Cho said in a statement that it needs to press the water surface at the right speed for an adequate amount of time to achieve jumping. A water strider can do it flawlessly. Its legs have slightly curved tips that increase the surface area the insect uses to press against the water with maximum force without breaking the surface tension of the water.
Researchers at Seoul National University analyzed the insect’s motion to understand how it accomplishes the jump. Then they joined hands with their counterparts at Harvard University to develop a small robot based on the same principles a water strider uses. Findings of the study were published in the latest issue of Science journal.
The most fascinating locomotion in nature
They created a tiny robot that exerts up to 16 times its own weight on the water surface without breaking the surface tension of the water. It achieved the same height and momentum generated during a rapid jump on the solid ground, but the robot can do so on the water. This small robot is powered by an alloy that can be stretched, but swings back to its original length when heated. The alloy served as a contracting spring pulling on the robot’s highly water-repellent legs.
Kyu-Jin Cho said the study was conducted to understand “one of the most fascinating kinds of locomotion in nature.” The project was partially funded by South Korea’s Defense Acquisition Program Administration. It would be interesting to see if the robot is used in military applications.