Expanding polymer enables self-folding without heating or immersion in water
As 3-D printing has become a mainstream technology, industry and academic researchers have been investigating printable structures that will fold themselves into useful three-dimensional shapes when heated or immersed in water.
In a paper appearing in the American Chemical Society’s journal Applied Materials and Interfaces, researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and colleagues report something new: a printable structure that begins to fold itself up as soon as it’s peeled off the printing platform.
One of the big advantages of devices that self-fold without any outside stimulus, the researchers say, is that they can involve a wider range of materials and more delicate structures.
“If you want to add printed electronics, you’re generally going to be using some organic materials, because a majority of printed electronics rely on them,” says Subramanian Sundaram, an MIT graduate student in electrical engineering and computer science and first author on the paper. “These materials are often very, very sensitive to moisture and temperature. So if you have these electronics and parts, and you want to initiate folds in them, you wouldn’t want to dunk them in water or heat them, because then your electronics are going to degrade.”
To illustrate this idea, the researchers built a prototype self-folding printable device that includes electrical leads and a polymer “pixel” that changes from transparent to opaque when a voltage is applied to it. The device, which is a variation on the “printable goldbug” that Sundaram and his colleagues announced earlier this year, starts out looking something like the letter “H.” But each of the legs of the H folds itself in two different directions, producing a tabletop shape.
The researchers also built several different versions of the same basic hinge design, which show that they can control the precise angle at which a joint folds.
Self-folding printable structures and 4D Printing will be among the topics discussed during the 4D Printing & Meta Materials Conference, on April 18, 2018 in The Netherlands. For more info about the conference and registration, visit https://www.4dpmmconference.com/