To create a robot that could successfully launch itself from the surface of water, the researchers from Seoul National University and Harvard University studied how water striders (Gerridae) jumped on water.
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The prototype is two-thousandths of an ounce and has a 3/4-inch long body. But previous robots weren’t quite as faithful to the water striders that they were modeled after; the Waterloo robot used wide paddles for its jumps and weighed about a thousand times more than a water strider. The cohesion between water molecules makes them want to hold on to each other, at least till there is enough force to break them apart. What’s more, water striders support themselves on their trasi-the center segment of their foot-by surface tension alone. But when jumping] on water, legs will easily penetrate the water, and even if you can jump on water, the jumping height will [usually] be lower than jumping on ground. The spring-loaded, ultra-light robot manages to get to about 14cm above water. By wicking their curved legs inward, across the water, keeping much of their leg in contact with the tiny divots each leg creates.
Despite what Jesus would have you believe, walking on water is no great achievement – insects have been doing it for millennia.
“What we have devised was a very small bio-inspired jumping mechanism called a torque reversal catapult mechanism which applies a small force initially then the force increases gradually and thereby we can maximise the momentum transfer without exceeding the maximum surface tension force“.
“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”, said Kyu Jin Cho, Associate Professor in the Department of Mechanical and Aerospace Engineering and Director of the Biorobotics Laboratory at Seoul National University. The achievement, described in Science today, means that an army of small, robotic creatures might one day help search for flood survivors – or they could end up being used to creep on your enemies, according to the researchers.
Mimicking a real-life bug known as the water strider, a team of global researchers has created a robotic insect that can jump on water without making a splash.
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He added: ‘Jumping on water is a unique locomotion mode found in semi aquatic arthropods, such as water striders.
