SIN -- Water-resistant Mesh, Orion K. April 2009

Scientists from the Harbin Institute of Technology in China have made a mesh that traps air, making it buoyant (by repelling water), reports Charles Q. Choi in an article entitled Float Your Boat. This article appears on page 28 of the May 2009 issue of Scientific American.

The water retardant mesh is made out of copper wire approximately 200 microns in diameter, with holes of about the same size. First, the researchers submerged the mesh in a solution of silver nitrate, then in acid. This resulted in silver leaf-like structures about seven microns high. The idea for this was found in the hairs of the diving beetle Dytiscus marginalis. The “leaves” trap a “film” of air (the air “sticks to” the leaves), this air film stops water infiltration and gives the mesh its buoyancy. In tests with boats of about an inch square, the leaf covered meshes supported three times as much mass as a mesh without the leaves.

The researchers concede that this repulsion, and resulting buoyancy, would not be enough to float large vessels (such as oil tankers, or even rowboats); however, they say that this could help in development of new miniature aquatic robots.