US team uses light to control origami structures

Described in the journal Science Advances, the work involves using a variety of coloured inks on different hinges of the structures. Because different colours absorb light in their own way, the North Carolina team was able to control the sequence of folding using a range of wavelengths.

"A longstanding challenge in the field has been finding a way to control the sequence in which a 2D sheet will fold itself into a 3D object," said Michael Dickey, a professor of chemical and biomolecular engineering at NC State and co-corresponding author of the paper.

"And as anyone who has done origami - or folded their laundry - can tell you, the order in which you make the folds can be extremely important."

As an example, if one hinge is printed in yellow and another hinge is printed in blue, it’s possible to make the yellow hinge fold using blue light. As blue ink doesn’t absorb blue light, the blue hinge won't fold. However, by subsequently exposing the sheet to red light, the blue hinge can then be activated.