Fiber structure helps sucker fish "hitchhike"
The researchers demonstrated that the new suction cup can hold various objects. Photo source: substance
As a well-known free traveler in the ocean world, a grouper hitchhiker uses a suction cup evolved from its dorsal fin to tightly attach to the surface of its host. Recently, researchers from Beijing University of Aeronautics and Astronautics found that the strong adsorption capacity of the fish comes from the special structure inside the suction cup lip. The related paper was published in substance on February 27.
Wen Li, a professor at Beijing University of Aeronautics and Astronautics and co-author of the paper, mentioned that the shape and swimming ability of the fish itself are not enough to make it have a survival advantage in nature, so it evolved its first dorsal fin of its head into a suction cup, so that it can carry other sea creatures' hitchhikes, so as to achieve predation and reproduction.
It is also known as a slovenly fish or sucker fish. Its suction cup is strong enough to keep its adsorption on dolphins jumping out of the water and rotating at high speed. In order to explore the mystery, the researchers studied the soft lips of suction cups. They found that the lip ring had a unique structure between the upper and lower epidermis: vertical collagen fibers. The elastic energy provided by the fibrous structure can maximize the contact area between the suction cup and the object, and reduce the deformation of the lip ring to maintain its adhesion. It is also the first time for the academic circles to reveal the structure of the labial ring in detail.
Inspired by the fish, researchers designed a bionic suction cup with vertical nylon fiber by electrostatic flocking, which uses electric charge to arrange the fibers. Compared with the pure silica gel suction cup, the adsorption force of the bionic suction cup is increased by 62.5%, and the adsorption time is increased by 3.4 times. In addition, the fiber-reinforced bionic suction cup can hang objects with large weight, irregular shape and different surface roughness.
Next, the researchers will study and imitate the structure of epidermis and hypodermis to improve the current bionic suction cup. Introduce environmentally friendly and biodegradable materials such as silk instead of nylon. The development of normal fiber structure can also be applied to software robots to achieve precise and complex motion by controlling the degree of deformation.
Related paper information: http://dx.doi.org/10.1016/j.matt.2020.01.018
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