Clean the Hull by Flicking a Switch

Duke University engineers have developed a hull coating that dislodges bacteria when an electrical current is applied.

The material works by physically moving at the microscopic level, knocking the bacteria away. This avoids the use of bacteria-killing paints, which can contain heavy metals or other toxic chemicals that might accumulate in the environment and unintentionally harm fish or other marine organisms.

"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. "This deformation can effectively detach biofilms and other organisms that have accumulated on the surface."

The researchers tested their approach in the laboratory with simulated seawater, as well as on barnacles. These experiments were conducted in collaboration with Daniel Rittschof the Duke University Marine Lab in Beaufort, N.C.

Keeping bacteria from attaching to ship hulls or other submerged objects can prevent a larger cascade of events that can reduce performance or efficiency. Once they have taken up residence on a surface, bacteria often attract larger organisms, such as seaweed and larva of other marine organisms, such as worms, bivalves, barnacles or mussels.

The project is funded by the U.S. Office of Naval Research and the MRSEC. Other members of the Duke team are Phanindhar Shivapooja, Qiming Wang and Beatriz Orihuela.