The tiny stents get their so-called "shape memory" from an unusual alloy called nitinol, which exhibits one shape when cool, but forms another when heated. This property has made the alloy useful in an increasing number of small-scale medical and consumer products that depend on motion, yet do not have enough space for motors or pumps.

Intrigued by the alloy's biomedical potential, University of Florida researchers have recently begun investigating it for the much larger application of prosthetic limbs.

Under the direction of mechanical engineering Professor Carl Crane, UF master's student Jose Santiago-Anadon built a nitinol device that can move the equivalent of more than 100 pounds. While the apparatus is merely a weight-lifting machine now, the hope is the research will one day lead to a nitinol "muscle" that can mimic the strength and motion of the real thing doing the work of a tendon or other major muscle in a next-generation prosthesis.

"Basically, it's almost the size of a tendon or other large muscle," Crane said. "It requires a lot of electricity, but it does not require the kind of bulky motors or hydraulic pumps that drive similar devices."

Nitinol was discovered by U.S. Navy researchers in the early 1960s. The name combines the abbreviations for nickel and titanium with the acronym for the Naval Ordnance Laboratory, where the first research on the alloy was done.

For years, nitinol was used only in niches. But the development of medical applications has spurred the creation of other nitinol commercial products, including showerheads that automatically shut off the flow of water before it becomes hot enough to scald a person.

The shape memory effect occurs in response to heat, which can be generated through electricity or any other energy source. Indu
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Contact: Jose Santiago or Carl Crane
jrsan@ufl.edu
352-392-9461
University of Florida
14-Aug-2002