28 July 2008

‘Dinosaur eel’ points to future body armour

Agence France-Presse
An extraordinary African fish that inhabits muddy pools, and whose lineage can be traced back 96 million years, could be the model for the light, bomb-proof body armour of the future.
Dinosaur eel

Heavily armoured: A Senegal birchir in an aquarium. Credit: MIT

PARIS: An extraordinary African fish that inhabits muddy pools, and whose lineage can be traced back 96 million years, could be the model for the light, bomb-proof body armour of the future.

So say Pentagon-backed scientists who have pored over the scales of Polypterus senegalus, also called the Senegal bichir or the dinosaur eel.

Long and skinny and of ancient heritage, the 40-centimetre-long predator has multiple layers of scales that first dissipate the energy of a strike, then protect against any penetration to the soft tissues below and finally limit any damage to the shield to the immediate area surrounding the assault.

Experts at the Massachusetts Institute of Technology (MIT), in Boston, U.S., used nano-scale measurements to look at several scales that were harmlessly removed from a living fish. They found the scales – about 500 millionths of a metre thick – have four layers. The tiny shield was then put to the test, in a simulation of a biting attack.

“Energy-dissipating mechanisms”

The team believe the scales’ protection is remarkably effective because of the different composite materials, the geometry and thickness of each of these layers. The overlapping junctions between the layers themselves also play an important role.

The design is “fascinating, complex and multiscale,” say the scientists who detail the discovery in the British journal Nature Materials.

“Such fundamental knowledge holds great potential for the development of improved biologically-inspired structural materials,” said Christine Ortiz, an MIT associate professor in materials science and engineering and lead author of the study.

“Many of the design principles we describe – durable interfaces and energy-dissipating mechanisms, for instance – may be translatable to human armour systems,” said Ortiz.

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