Curious about the physical conditions that enable aquatic animals to leap out of water in such a graceful manner—researchers at Cornell University were inspired to design a robotic system based on jumping aquatic animals specifically jumping copepods (tiny crustaceans) and frogs. Their study illuminated the role of fluid dynamics in allowing such animals to jump.
Image of a copepod (Gaussia princeps)
Credit: Solvin Zankl/naturepl.com via BBC Earth
Results of the study were presented at the American Physical Society's Division of Fluid Dynamics 71st Annual Meeting. "We collected data about aquatic animals of different sizes -- from about 1 millimeter to tens of meters -- jumping out of water, and were able to reveal how their maximum jumping heights are related to their body size," said Sunghwan Jung, an associate professor of biology and environmental engineering at Cornell University.
Animals will move in and out of water for various reasons such as escaping predators, catching prey, or for communicating purposes. "But since water is 1,000 times denser than air, entering or exiting water requires a lot of effort, so aquatic animals face mechanical challenges," explained Jung. "We're trying to understand how biological systems are able to smartly figure out and overcome these challenges to maximize their performance, which might also shed light on engineering systems to enter or exit air-water interfaces.”
The designed robot features a simple design “akin to a door hinge with a rubber band”. The rubber band is wrapped around the outer perimeter of a 3D-printed door hinge—which is held by a tiny wire. The wire allows the door hinge to flip back when the fluid is pushed downward. "This robot shows the importance of entrained water while an object jumps out of the water," says Jung. "This system might then be able to be used for surveillance near water basins.”
Watch this video below of an animal-inspired robot jumping out of water featuring the 3D-printed door-hinge-like wrapped with an elastic band and placed within a water tank. A thin metal wire is seen holding the robot in place and is cut via an electric shock. The robot the flaps downward and jumps out of the water.