A new biomimetic moving surface

Undulatory topographical waves for flow-induced foulant sweeping.

Stingray, any of several flat-bodied rays noted for the long, sharp spines on their tails. Stingrays use their paired pectoral fins to stabilize their movement through the water and sweep away sandy foreign particles from its surface.

Inspired by such natural processes, UNIST scientists have created a new biomimetic ‘moving’ surface inspired by the biomechanics of the pectoral fins of the Batoidea. They used magnetoresponsive composite materials. They proposed a magnetically responsive multilayered composite that can generate coordinated, undulatory topographical waves with controlled length and time scales as a new class of dynamic antifouling materials. The undulatory surface waves of the magnetic composite induce local and global vortices near the material surface and thereby sweep away foulants from the surface, fundamentally inhibiting their initial attachment.

The current biomimetic advancements impersonate natural chemical defense mechanisms utilized by living organisms to prevent fouling organisms from attaching to their surfaces. However, as the coating wears out, this prompts changes in the surface composition, consequently losing its highlights. To tackle this issue, scientists have concocted systems that use repeatable changes looking like wrinkles, yet this was generally centered around matters identified with the evacuation of adhering microbes, subsequently restricts starting foulant attachments.

This new study overcomes these limitations by mimicking the functions of living things, instead of their surface characteristics.

Hangil Ko (Department of Mechanical Engineering, UNIST), the first author of the study, said, “As stingrays swim, they generate a wake of vortices with their fins. Such vortex serves as a protective barrier against contaminants from accessing their fin surfaces.”

“Their fins generate not only vortices but also other forces, like shear stress. This special force acts horizontally on the surface as if it were sweeping with a broom to prevent microbial attachment.”

 Undulatory topographical waves of the dynamic composite modulated by the controlled magnetic field.
Undulatory topographical waves of the dynamic composite modulated by the controlled magnetic field.

Hyun-Ha Park in the Doctoral Program of Mechanical Engineering at UNIST, the co-author of the research, said, “The newly developed “moving antifouling surface” provides an effective means for efficient suppression of biofilm formation. Like the fins of the Batoidea, this sweeps away foulants from the surface, thus fundamentally inhibiting their initial attachment.”

Professor Hoon Eui Jeong in the School of Mechanical Aerospace and Nuclear Engineering at UNIST said, “Our findings provide an effective means for efficient suppression of biofilm formation without surface modification with chemical moieties or nanoscale architectures. Thus, it can be applied to a wide range of applications, such as medical devices and marine facilities.”

Scientists presented their paper in the journal Science Advances.

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