Thaindian News

Washington, Sep 25 (IANS) Researchers have figured out how to produce a low cost shape-shifting “memory” foam, which could lead to more widespread applications in surgical positioning tools and valve mechanisms.
David Dunand, materials science professor at Northwestern University, has been collaborating with Peter Müllner, his counterpart at Boise State University, on a project focused on a nickel-manganese-gallium alloy that changes shape when exposed to a magnetic field.

The alloy retains its new shape when the field is turned off but returns to its original shape if the field is rotated 90 degrees, demonstrating “magnetic shape-memory”.

The alloy can be activated millions of times, and it deforms reliably as a result. This property could be an advantage in fast-operating actuators (mechanical devices for moving or controlling a mechanism or system) in ink jet printers, car engines and surgical tools.

To date, the magnetic shape-memory effect has occurred only in nickel-manganese-gallium single crystals, which are much more difficult and expensive to create than the more common polycrystals.

Now, Dunand, Müllner and colleagues have created polycrystalline foams that can be easily processed with shape-shifting properties resembling those of the much more expensive single crystals.

They did this by introducing small pores into the “nodes” of their original metallic foam, which, much like a sponge, consisted of struts connected by relatively large nodes.

Adding a second level of porosity allowed for deformation and retention in the polycrystalline foam of some of the shape-memory properties.

Northwestern and Boise State have jointly filed a patent application.

The results were published online in Nature Materials.