Scientists from the University of Rochester’s Institute of Optics have developed a process that turns ordinary aluminum tubes into unsinkable metal tubes that float on water without sinking. The researchers behind the new technique said their superhydrophobic (SH) tubes stay afloat no matter how long they are forcibly submerged or how heavily they are damaged.
“In this work, we demonstrate a metallic SH tube with a reliable underwater buoyancy, high adaptability to violent environments, and strong resistance to mechanical abrasion and structural damage,” the researchers explain in a published study.
Along with unsinkable maritime structures for commercial and industrial applications, such as cargo transportation and environmental monitoring, the Rochester team proposed a conceptual design for a green, sustainable wave-based energy-harvesting device that maintains performance even if the SH tubes are damaged or degrade.
Unsinkable Metal Tubes Use Trapped Air Bubble Like Diving Bell Spiders
According to a statement detailing the unsinkable metal tubes, team leader Chunlei Guo, a professor of optics and physics and a senior scientist at URochester’s Laboratory for Laser Energetics, said the team’s process involves etching the interior of the tubes with a series of micro-pits and nano-pits. When these surfaces are exposed to water, these pits turn them into a superhydrophobic surface that repels water and stays dry,
The team originally demonstrated the concept in 2019 by etching the surfaces of two disks and then sealing them together to create a superhydrophobic buoy. However, experiments revealed that the double-disk design lost buoyancy when it was turned “at extreme angles.”
In the new approach, the etched inner surface of the tubes traps a stable air bubble between it and the entering water. The result is an unsinkable metal tube that can be twisted, bent, punctured, or repeatedly submerged without losing buoyancy. The researchers said that their unsinkable tubes’ “remarkable floating ability” comes from the trapped air bubble.
“Besides being able to float back to the surface even after being fully forced into water, the SH tube can also maintain buoyancy under severe tilting, water impact, and even under severe structural damage,” they explained.
The researcher also credited their SH tubes’ seemingly impossible ability to remain afloat after being fully submerged to a design modification. According to Guo, their updated design included the addition of an internal ‘divider’ so that “even if you push it vertically into the water, the bubble of air remains trapped inside and the tube retains its floating ability.”
The researchers said the ability to trap a bubble of air to maintain buoyancy is like that used by water striders to skate across a water’s surface without becoming submerged, by diving bell spiders to stay afloat, or by fire ants to combine their hydrophobic bodies into floating “rafts.”
Tests Reveal Severely Damaged Tubes Retain Buoyancy
Guo said his team tested their unsinkable tubes in some “really rough environments for weeks at a time,” but they showed no reduction in overall buoyancy. The professor also noted that his team could “poke big holes in them,” and yet, they retained their superhydrophobic qualities.
“We showed that even if you severely damage the tubes with as many holes as you can punch, they still float,” Guo explained.
When discussing potential applications of the unsinkable metal tubes, Guo’s team said the buoyancy tests were successful with different tube lengths, including some up to half a meter. However, they suggest their process is inexpensive, easy to replicate, and scalable to commercially viable SH platforms for “load-bearing” structures. This includes using unsinkable metal tubes as the basis for rafts, ships, buoys, and industrial floating platforms.
“The SH tubes assembly can be used to construct large vessels, watercrafts, floating platforms, and buoys for marine applications,” they explained.
The study authors also suggest their approach could help develop advanced renewable energy devices that operate in ocean environments.
“As an example, we demonstrate a floating SH electrical energy generator to harvest ocean tidal energy,” they explained.
The study “Geometry-Enabled Recoverable Floating Superhydrophobic Metallic Tubes” was published in Advanced Functional Materials.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.