Polymers that Shift and Shape

Jan. 11, 2008

Georgia Tech researchers develop smart materials for biomedical applications.

The human body is a harsh environment for implantable materials, what with all the tissue and bodily fluids in which they must reside. Researchers at the Georgia Institute of Technology are developing materials to weather those severe conditions without losing functionality, stability or biocompatibility. These so-called "shape-memory polymers" can temporarily compress or expand in size, ultimately assuming their permanent shape with the application of light, heat or a chemical trigger.

The characteristics of polymers make them good candidates for biomedical applications, says Georgia Tech professor Ken Gall. That's because they more closely resemble soft biological tissue than does metal, and they can be designed to gradually dissolve in the body.

Gall's research group already has developed a shape-memory polymer stent that can be compressed and threaded through the body into a blocked artery just like a conventional stent. The body's heat then triggers the polymer to expand into its permanent shape.

Georgia Tech professor Ken Gall reaches into a thermo-mechanical test frame, used to measure the properties of polymers under conditions mimicking the human body.Gall and fellow researchers also are exploring how these polymers may be used as a deployable neuron probe, as well as in spinal applications. The scientists are developing shape-memory polymers that are stretchy and support weight similar to that of human spinal disks. "This would improve the deliverability and life of artificial disks," Gall says. "Essentially, we're just trying to engineer tougher synthetic polymers that can be easily delivered."

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