University of Rochester researchers, inspired by diving spiders and fire ants, have created a metallic structure that’s so water repellent, it refuses to sink—irrespective of how often it’s forced into water or how a lot it’s broken or punctured, says Chunlei Guo, professor of optics and physics, whose lab describes the structure in ACS Utilized Supplies and Interfaces
The structure makes use of a groundbreaking technique the lab made for utilizing femtosecond bursts of lasers to “etch” the floors of metals with intricate micro- and nanoscale patterns that trap air and make the facades superhydrophobic, or water repellent.
The researchers discovered, however, that after being submerged in water for long intervals, the surfaces might start to lose their hydrophobic qualities.
Enter the spiders and fire ants, which may survive lengthy durations under or on the floor of water. Argyroneta aquatic spiders, for example, create a dome-shaped underwater web—a so-called diving bell—that they fill with air carried from the floor between their super-hydrophobic legs and guts. Similarly, fire ants can form a raft by trapping air among their superhydrophobic bodies.
Guo’s lab created a structure by which the treated surfaces on two parallel aluminum plates face inward, not outward, so they are enclosed and free from external wear and abrasion. The surfaces are separated by merely the right distance to lure and hold sufficient air to keep the construction floating- in essence, creating a waterproof compartment.
Even after being forced to sink for two months, the structures instantly bounced back to the floor after the load was released, Guo says. The structures retained this ability even after being punctured multiple times because air stays trapped in the remaining components of the compartment or adjoining structures.