What Is This

What is This?

What Is This

spicule San Francisco Earthquake

The image in the foreground is a graphical representation of the 3 meter long glassy anchor spicule from the deep sea sponge, Monorhaphis chuni, highlighting its transparency and remarkable flexibility. The background image illustrates its micro-architecture which consists of layers of silica separated by thin organic inter-layers measuring less than 50nm thick. Following loading, fracture of this laminated structure involves cracking of the constituent silica and crack deflection through the intervening proteinaceous layers, leading to the stair-step pattern in the image. Crack deflection mitigates the high stress concentration that would otherwise be present at the crack tip, resulting in high spicule strength and toughness. This design strategy thus prevents the structure from failing catastrophically as one would expect for a non-laminated glass rod (note the fracture similarities between the spicule and the brick street following the 1906 San Francisco earthquake). It is hoped that by understanding structure-function relationships in these materials, that design lessons can be learned that will ultimately guide the development of more damage-tolerant synthetic structural glasses for a wide range of applications.

Effects of Laminate Architecture on Fracture Resistance of Sponge Biosilica: Lessons from Nature
A. Miserez, J. C. Weaver, P. J. Thurner, J. Aizenberg, Y. Dauphin, P. Fratzl, D. E. Morse, F. W. Zok
Advanced Functional Materials 2008 (in press)