Engineers at the University of Rochester have developed a way to make ordinary aluminum unsinkable even when it’s punctured, submerged, or battered by rough conditions. The innovation uses microscopic laser etching to create superhydrophobic metal tubes that repel water and trap air, keeping them buoyant under extreme circumstances.
Published in Advanced Functional Materials, the research offers a promising step toward building long-lasting, damage-resistant floating structures. Think marine vessels, rescue equipment, and platforms that harness wave energy.
How the tubes stay afloat
The team, led by optics and physics professor Chunlei Guo, modified the inner surface of aluminum tubes by etching it with lasers. The process creates micro- and nano-scale pits that make the metal extremely water-repellent. When the treated tube is submerged, this textured surface captures a stable air pocket inside, acting as a built-in flotation system.
To ensure stability from all angles, the researchers added a divider to the center of each tube. This feature prevents air from escaping, even if the tube is pushed vertically into water.
“This design helps maintain the air bubble inside the tube, so it keeps floating no matter the position,” Guo said.
The mechanism is reminiscent of amazing examples in nature of hydrophobic engineering at work, like how diving bell spiders carry air underwater or how fire ants form buoyant rafts during floods.
Durable, adaptable, and scalable
This isn’t the lab’s first venture into floating materials. In 2019, Guo and his team created superhydrophobic disks that floated when sealed together. But their performance faltered under extreme angles or turbulence.
The new tube-based design addresses those limitations with a simpler, more robust structure.
The researchers tested the tubes in varied, challenging environments over several weeks and found that buoyancy remained unaffected. Even after punching multiple holes into the metal, the tubes continued to float. “We showed that even if you severely damage the tubes with as many holes as you can punch, they still float,” Guo said.
The team also tested different lengths, trying out up to nearly half a meter, and demonstrated that the design could be scaled up and linked together to create floating platforms.
A foundation for floating energy systems
Beyond buoyant materials, the researchers explored practical applications. One experiment showed how rafts built from these tubes could be used to harvest energy from wave motion, a promising development for off-grid power or renewable energy systems on the water.
That added functionality could make this technology especially valuable in remote or offshore environments, where both stability and low-maintenance design are key.
The research was funded by the National Science Foundation, the Bill and Melinda Gates Foundation, and the University of Rochester’s Goergen Institute for Data Science and Artificial Intelligence.
What comes next
While still in the research phase, the superhydrophobic tube design offers an adaptable foundation for various marine technologies such as unsinkable buoys, modular docks, emergency rescue gear, and more. It could even inform future ship designs that prioritize resilience without sacrificing simplicity.
With further development, these laser-treated tubes might become an elegant, scalable solution for some of the challenges of life on and near the water.
Source study: Advanced Functional Materials—Geometry-enabled recoverable floating superhydrophobic metallic tubes
