Below are a few scholarly articles providing details pertaining to the mechanism of the chameleon's tongue:
-Schwenk, K., and D. A. Bell. "A cryptic intermediate in the evolution of chameleon tongue projection." Experientia 44.8 (1988): 697-700.
Available here.
-de Groot, Jurriaan H., and Johan L. van Leeuwen. "Evidence for an elastic projection mechanism in the chameleon tongue." Proceedings of the Royal Society of London-B 271.1540 (2004): 761.
Available here.
-Herrel, Anthony, et al. "The mechanics of prey prehension in chameleons." Journal of Experimental Biology 203.21 (2000): 3255-3263.
Available here.
-WAINWRIGHT, PETER C., DAVID M. KRAKLAU, and ALBERT F. BENNETT. "Kinematics of tongue projection in Chamaeleo oustaleti." Journal of experimental biology 159.1 (1991): 109-133.
Available here.
Below are two links that provide background information about other research groups' attempts at technology mimicking a chameleon's tongue.
Alexis Debray's artificial chameleon tongue
Alexis Debray is an engineer at Canon in Tokyo, Japan. His attempt to mimic the tongue utilizes the concepts of acceleration due to magnetism. His system consists of a line attached to a magnet that is accelerated through a coil gun. With an elastomer at the end of the line (tip), the technology can be used in machine lines to put delicate parts on cameras.
* This is one of the ideas that the group considered using, however, implementing it in a gun-shaped device appeared more complicated and difficult than the current design.
Japanese Reserachers' artificial chameleon tongue
The creation of this artificial chameleon tongue was actually a by-product of two Japanese researchers' attempt to create an entire artificial chameleon. The researchers started with the most important part of the chameleon, its tongue. The system is simple in that it relies on an air cannon projecting a magnet attached to an elastic cord. This setup was able to snap up objects .7 m away with 90% accuracy.
* While this technology is incredibly accurate and can snap up objects instantly, the setup is not practical in a mobile sense because it can only catch magnetic materials and needs a static break-beam sensor to tell it when to fire.
