Decades ago a popular novelty promotional item was sometimes included with various purchases, and invigorated the imaginations of children and adults alike. That item typically came in the form of a highly compressed sponge-like material, and though it varied in size and color, it usually was shaped like an aspirin tablet, but was often much larger. When placed in water the object would dramatically expand while taking on a completely different and predetermined shape. Some of those tablets would take the form of a seahorse, a small house, or any animal or object the imagination of the designer could conjure up.

"New Lamps for Old" & 4D Printing

The phrase "new lamps for old" springs from the age-old tale of Aladdin and a sorcerer's plan for taking possession of a magic lamp by offering a new lamp in exchange for the old and quite valuable magic lamp. In the 2013 version of this tale we see the continuation of a well-known technique for self-assembling, or at least self-morphing objects as applied to the more recent 3D printing craze. The number four in the term 4D printing would seem to represent the property or act of transformation.

Tibbits and many other researchers have developed a technique by which a 3D printer can combine layers of typical materials with other so-called "smart" materials. When exposed to a change-agent such as water, the patches or layers of the mutable materials either contract or expand to alter the shape of an object into a predesignated and completely different form. One working example offered by the consortium is a small plastic tube that shapes itself into a rectangular box when exposed to water as the change-agent.

So what does 3D printing have to do with it? Probably not much, as this old-is-new-again technology continues to develop; because for hundreds of years there have been dozens or perhaps thousands of methods for combining layers of materials, and there are many ways to achieve results with mutable or self-morphing materials without the use of 3D printing.

Everything Old is New Again

A good example of how mutable layers of materials have been utilized in technology of the day is a design that has been in use for perhaps a hundred years in the form of wall-mounted bi-metallic strip thermostats. Those devices incorporate a coil made of two metals that have different expansion and contraction rates thereby enabling changes in air-temperature to become the change-agent that turns the heating or cooling system on or off.

MIT researchers are hopeful for a variety of materials and applications using change-agents such as pressure, light, microwaves, electricity, chemical reactions, and of course water, and temperature. Hopeful may be a key word, and those researchers envision applications in aerospace, furniture, pipelines, and even bicycles and buildings.