Carbon Nanotubes Outstick Gum-Footed Gecko

Michael A. Greenwood

Sorry, gecko. Your reign as the undisputed climbing king may be over.

But take comfort. Your fabled foot has benefited science. And, hey, you still have that spot with Geico.

Shown are the bottom of a gecko’s foot (A) and a close-up revealing the setae terminating into thousands of smaller spatulas (B). Researchers imitated nature’s design using multiwalled carbon nanotubes (C and D). Reprinted with permission of PNAS.

A team of researchers has created an ultrasticky material with carbon nanotubes, modeled on the intricate design found on the tiny reptile’s sole. The tape (appropriately called gecko tape after its inspiration) supports more weight than a gecko’s foot and could be used for applications such as wall-climbing robots.

The researchers, from the University of Akron in Ohio and from Rensselaer Polytechnic Institute in Troy, N.Y., reported their results in the June 26 issue of PNAS. They used a JEOL Ltd. scanning electron microscope to explore the lizard’s talented toes. A gecko’s foot can stick to vertical surfaces, and even to ceilings, because of an intricate arrangement of protrusions called setae. The setae split at their ends into even smaller filaments known as spatulas. These can get inside virtually any crack or crevice, giving the creature its famed scaling ability.

The team replicated the setae with bundles of micrometer-size multiwalled carbon nanotubes. The spatulas were simulated with nanometer-size bundles of the same material. Experiments showed that the gecko tape supported a shear stress nearly four times greater than a gecko’s foot. The tape can be used repeatedly and can stick even to nonstick Teflon.

With results like that, Spider-Man might want to consider an upgrade.