New biopolymer changes structure like sea cucumber

BEIJING, June 24 (Xinhuanet) -- A biopolymer that mimics the structure of a sea cucumber, allowing it to change from flexible to rigid to squeeze through a narrow opening or ward off predators, has been created in the United States by Case Western University researchers.

It is known that sea cucumbers have skin composed of very fine cellulose fibers. When attacked, surrounding cells secrete molecules that cause these "whiskers" to bind together, forming a kind of protective armor. When relaxed, other cells release plasticizing proteins to loosen the fibers, allowing the creatures to flow easily through crevices.

Researchers isolated the cellulose fibers from the surface of creatures similar to sea cucumbers. The researchers then combined the fibers with a rubbery polymer mixture. The fibers formed a kind of mesh through the body of the material, reinforcing the softer polymer. The fibers hold it together, creating an inflexible material.

"It's like a three-dimensional web in which these nanofibers overlap at certain points, and wherever they overlap, they stick to each other," say researchers.

The researcher hope this rigid-yet-flexible material could be used in biomedical applications, like implantable electrodes that could record brain activity over long periods of time, without the scarring produced by conventional metal electrodes.

This material is a variation on the idea of shear-thickening fluids used in applications as varied as body armor and rehabilitative exoskeletons.

(Agencies)