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Material ‘wrinkles’ to allow ships to shake off scum, say researchers

Engineers from Duke University have discovered a way to help vessels shake off the unwanted accumulation of bacteria and other marine growth, known as ship scum, using stretching, pressure or electricity.

Engineers have designed a novel material that can be applied like paint to the hull of a ship and will be able to prevent bacteria from accumulating by dislodging it from the ship’s surface. Ship scum increases drag and reduces the energy efficiency of the vessel, in addition to preventing undersea sensors from working properly.

According to a news release from Duke University, the novel material works by physically moving at the microscopic level, removing the bacteria. This material prevents the ship’s maintenance crew from having to use bacteria-killing paints, which can contain heavy metals or other toxic chemicals that might harm fish or other marine organisms.

Researchers contend that this novel material has multiple applications, including possible use on the surfaces of artificial joint implants or water purification membranes, where the buildup of bacteria is an issue.

“We have developed a material that ‘wrinkles,’ or changes it surface in response to a stimulus, such as stretching or pressure or electricity,” said Duke engineer Xuanhe Zhao, assistant professor in Duke’s Pratt School of Engineering, in a statement. “This deformation can effectively detach biofilms and other organisms that have accumulated on the surface.”

Zhao has already successfully proven the ability of electric current to modify the surface of polymers.

“Nature has offered many solutions to deal with this buildup of biological materials that we as engineers can try to recreate,” said Gabriel López, professor of biomedical engineering and mechanical engineering and materials science.

“For example, the hair-like structures known as cilia can move foreign particles from the lungs and respiratory tract,” Lopez added. “In the same manner, these types of structures are used by mollusks and corals to keep their surfaces clean. To date, however, it is been difficult to reproduce the cilia, but controlling the surface of a material could achieve the same result.”

Researchers used simulated seawater to see if their novel material could remove bacteria from a ship’s surface.

This material should also help ships stay cleaner, as bacteria can often attract seaweed, larva and other marine organisms, like worms, barnacles or mussels.

“It is known that bacterial films can recruit other organisms, so stopping the accumulation process from the beginning in the first place would make a lot of sense,” Lopez said.

The study’s findings were recently described in detail in the journal Advanced Materials.

Photo credit: Phanindhar Shivapooja and Qiming Wang.