smart material

Material that responds in a predictable and useful – and often reversible – way to some external stimulus. For example, some smart materials have the ability to ‘remember’ shapes. If a piece of thermoplastic has a mark pressed into it while it is hot, and the unmarked part of the plastic is then sanded down to the level of the mark once the plastic has cooled, when reheated the piece of plastic where the mark was made will return to its original position, giving a raised effect. This is known as plastic memory.

Shape memory alloys (SMAs), often titanium-nickel alloys, may have their shape or length altered by heating, external forces, voltage, or magnetism, but will return to their original shape or size once this input has been removed. This effect can be repeated over and over in order to drive complex mechanical and electrical systems.

Other smart materials include piezoelectric ceramics and polymers, and magnetic SMAs.