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The serendipitous discovery of Nitinol, "the metal with a memory", has revolutionized manufacturing and medicine as countless products that "think" for themselves, sense changes in themselves and their surroundings, and respond appropriately enter the marketplace (1). Discovered in 1958 by metallurgist William J. Buehler while he was seeking an alloy for missile nose cones that could better withstand reentry, and named Nitinol for Nickel Titanium Naval Ordnance Laboratory, this best-known example of a so-called "intelligent" or "smart" material undergoes changes that occur between two solid phases and involve rearrangement of atoms within a crystal lattice (2).Although many materials undergo such transformations, which are less familiar than phase changes between solid and liquid or liquid and gas, Nitinol is unusual in that when it undergoes a phase transition due to a temperature change, it changes its shape as well. It "remembers" its shape because the phase change (between austenite and martensite phases) affects its structure on the atomic level only, without disturbing the arrangement of the crystals-which would be irreversible (3-5). Consequently, Nitinol has been used in a number of scientific demonstrations and laboratory experiments (6-8). The mechanism of Nitinol's action is explained in detail elsewhere (1,4,5,8).Taiwan-born Frederick E. Wang, an authority on crystal physics, was recruited by Buehler to explain the mechanicalmemory property of Nitinol and to collaborate on its development. After leaving the Naval Ordnance Laboratory in 1980, he founded Innovative Technology International, Inc. (ITI). ITI produces and supplies Nitinol to manufacturers and has built prototypes of Nitinol-based engines that convert thermal energy to mechanical energy. Although the Nitinol engine is still years from production, other Nitinol products are already in existence and saving lives. These include sprinkler systems and automatic tap turnoffs. Nitinol-based fire sprinklers respond much more rapidly than conventional ones, while a Nitinol antiscalding device shuts off a tap whenever the temperature of the water exceeds a safe level. Other uses for Nitinol include medical and dental devices, eyeglass frames, pipe couplers for F-14 and F-16 fighter aircraft, greenhouse window hinges, and coffee-maker valves.

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