Using a 3D printer, people can already determine the length, width and depth of an object that they create. Thanks to research being conducted at the University of Colorado, Boulder, however, a fourth dimension can now be included – time. And no, we're not talking about how long it takes to 3D-print an item. Instead, it's now possible to print objects that change their shape at a given time.

The scientists, led by Prof. H. Jerry Qi, have developed a "4D printing" process in which shape-memory polymer fibers are deposited in key areas of a composite material item as it's being printed. By carefully controlling factors such as the location and orientation of the fibers, those areas of the item will fold, stretch, curl or twist in a predictable fashion when exposed to a stimulus such as water, heat or mechanical pressure.

A 4D-printed "polymer airplane" that folds itself into shape

The concept was proposed earlier this year by MIT's Skylar Tibbits, who used his own 4D printing process to create a variety of small self-assembling objects. "We advanced this concept by creating composite materials that can morph into several different, complicated shapes based on a different physical mechanism,” said Martin L. Dunn of the Singapore University of Technology and Design, who collaborated with Qi on the latest research.

This means that one 4D-printed object could change shape in different ways, depending on the type of stimulus to which it was exposed. That functionality could make it possible (for example) to print a photovoltaic panel in a flat shape, expose it to water to cause it to fold up for shipping, and then expose it to heat to make it fold out to yet another shape that's optimal for catching sunlight.

A paper on the research was recently published in the journal Applied Physics Letters.

Source: University of Colorado, Boulder