Water striders can easily skim and jump off the surface of water — a distinct advantage in the struggle for survival. This ability has inspired scientists to develop robots that can perform the same act.
Harvard researchers, together with colleagues from Seoul National University, have developed a new robotic insect capable of mimicking the unique qualities of water striders.
"Water's surface needs to be pressed at the right speed for an adequate amount of time, up to a certain depth, in order to achieve jumping. The water strider is capable of doing all these things flawlessly," said Kyu Jin Cho from the Biorobotics Laboratory at Seoul National University.
The legs of water striders are distinguished by rounded tips, which they utilize through a rotating movement. This discovery assisted the researchers in better understanding how skipping and jumping off water is accomplished.
The team developed and tested several different designs for the robots, as they worked to create more efficient prototypes. One set of experiments tested what would happen if force were applied quickly, revealing that such an action quickly broke through the surface of the water. Instead, the team discovered that jumping is best accomplished by maintaining contact with the liquid's surface for the longest time possible.
"Using its legs to push down on water, the natural water strider exerts the maximum amount of force just below the threshold that would break the water's surface," said study co-author Je-Sung Koh of Seoul National University in a press release.
The robotic insect is capable of exerting force as great as 16 times its own mass.
This skipping and jumping is more or less automatic for this insect without much in the way of a brain. Researchers hope to impart this ability to artificial robots based on water striders. Among other applications, the production of such small, inexpensive robots could see them swarming over a disaster area in search of survivors.
The water strider robots were constructed using a technique called pop-up manufacturing — similar to the design of children's pop-up books. This manufacturing method could be used to create micro-robots as well as other electronic devices, according to the researchers. The development would see the mechanical water striders jumping off water with much the same efficiency as similar devices taking off from land.
The development of tiny robots based on water striders was published in the journal Science.
