Sponge Builds a Better Glass Fiber

29 August 2003

Scientists say they have identified an ocean sponge living in the darkness of the deep sea that grows thin glass fibers capable of transmitting light at least as well as industrial fiber optic cables used for telecommunication. The natural glass fibers also are much more flexible than manufactured fiber optic cable that can crack if bent too far.

“You can actually tie a knot in these natural biological fibers and they will not break — it’s really quite amazing,” said Joanna Aizenberg, who led the research at Bell Laboratories.

The glassy sponge, nicknamed the “Venus flower basket,” grows the flexible fibers at cold temperatures using natural materials, a process materials scientists hope to duplicate in order to avoid the problems created by current fiber-optic manufacturing methods that require high temperatures and produce relatively brittle cable.

The sponge also is able to add traces of sodium to the fibers that increase their ability to conduct light, something that cannot be done to glass fibers at the high temperatures needed for commercial manufacturing, Aizenberg said.

“One of the challenges of technology is doping the glass structure with additives that improve optical properties,” she said. “If we understand exactly how we can deposit sodium in glass fibers at low temperatures as nature does, we can control all the properties.”

The sponge grows in deep water in the tropics. It is about a foot and a half tall (45 centimeters tall) with an intricate silica mesh skeleton that also serves as a home for shrimp. The glass fibers form a crown at its base that appear to help anchor the sponge to the ocean floor. The fibers are about 2 to 7 inches (5 to 17 centimeters) long, and each is about the thickness of a human hair.

“It’s such a wonderful example of how exquisite nature is as a designer and builder of complex systems,” said Geri Richmond, a chemist and materials scientist at the University of Oregon who was not involved in the study. “We can draw it on paper and think about engineering it, but we’re in the stone age compared to nature,” she said.

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