Gecko tape

Gecko Tape (Directional adhesion) is a new material still in the development stages.

Directional adhesion refers to the ability of an adhesive material to grip a load in one direction, and its ability to release its grip when the direction is reversed.

Description

Gecko Tape is so-called because it is based on the ability of the gecko to adhere to surfaces- regardless of said surfaces orientation- due to millions microscopic hairs on the geckos toes, called setae. Due to the principles of electrostaticism, the setae of the gecko have a non-zero electrical charge, which in close proximity to a surface, causes the two to be drawn together like two magnets.

The reason this works is that although an object normally has an "average" electromagnetic charge of zero, at the microscopic scale of the hairs the charge is continuously under flux- that is, changing- so that one side of an individual setae has a slight positive charge and the other a corresponding negative charge, and the point of interaction on the surface also has regional charge, causing a force of attraction (the van der Waals force) between the two.

This force, taking place as it does on a tiny scale between two objects in very close proximity to each other, is obviously extremely small itself, however, the number of these setae on the toe of a gecko number in the millions, and the combined force is enough that a gecko is able to hang from a ceiling- of any material- by one foot.

Scientists efforts to replicate the setae, commonly called gecko tape, are still in the early stages, but there has been success. (notably by Andre Geim's group)

References

* "The Physics of Superheroes", James Kakalios, pp. 174-175

* Gecko inspires sticky tape http://news.bbc.co.uk/2/hi/science/nature/2953852.stm

* Gecko tape will stick you to ceiling http://www.newscientist.com/article.ns?id=dn3785

* Will "Gecko Tape" Let Humans Climb Walls http://news.nationalgeographic.com/news/2003/06/0602_030602_geckotape.html