Smart plastics change shape ...( Cambridge Mass.--Picture a flower that...),Health

Cambridge, Mass.--Picture a flower that opens when facing the sunlight. In work that mimics that sensitivity to light, an MIT engineer and German colleagues have created the first plastics that can be deformed and temporarily fixed in a second, new shape by illumination with light having certain wavelengths. These programmed materials will only switch back to their original shape when exposed to light of specific different wavelengths.

The work, to be reported in the April 14 issue of Nature, could have potential applications in a variety of fields, including minimally invasive surgery. Imagine, for example, a "string" of plastic that a doctor threads into the body through a tiny incision. When activated by light via a fiber-optic probe, that slender string might change into a corkscrew-shaped stent for keeping blood vessels open.

What about staples that open on command, or paper clips that relax as soon as you don't need them anymore? Again, light could do the job.

"This is really a new family of materials that can change from one shape to another by having light shined on them," said Institute Professor Robert Langer of MIT.

Langer co-authored the paper with Andreas Lendlein, Hongyan Jiang, and Oliver Jnger. Lendlein, a former MIT visiting scientist, is institute director at the GKSS research center in Teltow, Germany. With Jiang and Jnger, he is also affiliated with RWTH Aachen, Germany.

SHAPE MEMORY

Plastics with "shape-memory" that can change shape in response to a temperature increase are well known. In 2001 Langer and Lendlein were the first to report biodegradable versions of these materials in the Proceedings of the National Academy of Sciences.

A year later the researchers introduced thermoplastic, biodegradable shape-memory polymers and demonstrated a nifty application giving a flavor of the innovation potential in the medical field: a smart suture that ties itself into the perfect k
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Contact: Elizabeth Thomson
thomson@mit.edu
617-258-5402
Massachusetts Institute of Technology
13-Apr-2005

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