Spiders taught scientists how to make unsinkable metal

Toss a coin into a fountain, and you know what will happen. Being denser than water, the metal sinks—ask any child. But new research has challenged centuries of certainty.

A team at the University of Rochester has etched aluminum tubes so that they won’t sink, even when damaged—a trick the scientists borrowed from spiders.

“You can poke big holes in them,” said Chunlei Guo, a professor of optics and physics at the University of Rochester and senior author of the research, in a press release. “We showed that even if you severely damage the tubes with as many holes as you can punch, they still float.”

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Many things in our lives repel water—examples include cooking oil, a rain jacket or a rubber glove. Scientists call this property hydrophobicity—from the Greek for “water fear”—but the secret to the metal tubes’ buoyancy lies in superhydrophobicity.

Guo’s team uses lasers to carve microscopic valleys into the aluminum that capture air: picture corduroy fabric shrunk down until it requires an electron microscope to see the ridges.

According to the press release, “the mechanism is similar to how diving bell spiders trap an air bubble to stay buoyant underwater.” The spiders live almost entirely underwater but still need to breathe. Their solution is to carry their own oxygen supply. Fine hairs covering their bodies trap air bubbles against their skin.

The metal tubes mimic those fine hairs, trapping their own air bubbles. Normally water would spread along the inside walls and push the air out. But when it hits the superhydrophobic texture, it bounces away. Surface tension—the same property that causes water to bead on a waxed car hood—prevents the water from entering the tube. As a result, the air stays inside, and the tubes remain buoyant.

The study, published on January 27, 2026, in Advanced Functional Materials, builds on Guo’s earlier work designing unsinkable metals. In 2019 his lab demonstrated the concept using laser-etched disks, but in turbulent water, the disks tipped, and the air escaped.

The new tubes solve that problem with an internal divider at the middle of the tube that helps trap the air in a confined chamber. “Even if you push it vertically into the water, the bubble of air remains trapped inside and the tube retains its floating ability,” Guo said in the same statement. The team tested the tubes in rough conditions for weeks and “found no degradation to their buoyancy,” he reported.

In nature, superhydrophobicity isn’t a new trick. The eyes of mosquitoes have water-repellent nanostructures that keep them clear, for example. And fire ants use their waxy, water-repellent coating and textured exoskeletons to trap air; during floods, thousands cling together to make buoyant, living rafts that can survive 12 days and possibly longer.

As for humans, this isn’t our first attempt at floating metal. In 2015 researchers at New York University embedded hollow silicon carbide spheres in a magnesium alloy to create a metal matrix composite lighter than water.

But the implications of Guo’s work go beyond the laboratory. Linked tubes could create weight-bearing rafts or ships. Engineers might be closing in on the dream of ships that stay afloat even as water pours into their hulls. One surprising application involves energy: Guo’s team demonstrated that rafts made of the tubes could harvest waves to generate electricity.

The tubes are currently nearly half a meter long, but Guo sees no barrier to increasing their size. The lasers are now seven times more powerful than they were in 2019, when Guo first attempted laser-etched metal disks. “The technology,” he said in the same statement, “could be easily scaled to larger sizes.”