Someone in an uncomfortable situation is often referred to as “a fish out of water.” Conversely, people who swim well are referred to as fish. Either way, almost all land animals struggle in the water and most water creatures flail on land. Perhaps it is not surprising then that land-dwelling humans would look to aquatic life to devise better machines to operate in the water. Specifically, water striders and rays recently inspired two different technologies for navigating over and through the water.
Walking on Water
Water striders perform the seemingly magical feat of walking on water. They not only move across the surface effortlessly, they can also jump over obstacles. Water’s high surface tension makes these movements possible. Studies of the strider’s feet helped a team of scientists develop a microrobot that uses the surface tension of water to mimic both the strider’s “walking” and jumping—and the machine weighs more than 1,000 water striders combined. The key innovation was finding a porous, highly water-repellant and lightweight material, in this case, a nickel-based foam.
Three pads made from this water-repellant foam provided the necessary force to keep the microrobot from sinking. Two similar paddles could then strike the water’s surface and provide the impetus for the robot to jump. Tests of the robot demonstrated a vertical leap of nearly 6 inches and the ability to jump forward by 14 inches.1 Such technology would provide microrobots great agility and adaptability as they gather data on remote, hard-to-reach bodies of water.
Cruising through the Deep Seas
A ray’s movement through the water matches (if not exceeds) the elegance of the water strider’s capacity to navigate across the water’s surface. Further, a ray travels effortlessly to places difficult to access with sensors deployed from a ship. By analyzing the swimming motion of a cow-nosed ray (one common to the Atlantic Ocean and Chesapeake Bay), a team of researchers built a prototype mechanical ray that mimics the movements of the actual organisms. Currently, scientists must control the prototype remotely, but they hope to manufacture a self-contained, autonomous machine that could be deployed for long periods of time. Such a device could carry instruments for monitoring spills, investigate delicate marine environments, and have potential military applications. Modeling the mechanical ray after existing creatures means that the machines operate without affecting the other organisms in their natural habitat. However, I would not want to be the shark that accidentally eats one of these things.
The number of biologically-inspired technologies continues to grow. From transportation networks to adhesives (at least two different kinds), myriad other examples show the awesome creative power of the Author of creation.