The team, from the John A. Paulson School of Engineering and Applied Sciences (SEAS), created a 3D-printable material that can be “pre-programmed with reversible shape memory.” The wool-like material can remember old forms and morph back into those, or transform into different shapes when a certain stimulus is applied.
It’s made using keratin extracted from recycled wool. Keratin is a fibrous protein that’s found in hair, which, of course, has a habit of returning to its natural form.
The researchers shaped a single chain of keratin into a spring-like structure. They twisted two of those together and used many such “coiled coils” to assemble large fibers. When a stimulus is applied to the material or it’s stretched out, those structures uncoil and the bonds realign. The material stays that way until it’s triggered to return to its original state, which is programmed with a solution of hydrogen peroxide and monosodium phosphate.
In one test, researchers programmed a sheet of keratin to have an origami star as its permanent shape. They dunked the sheet in water to make it malleable and rolled it into a tube. But when the team put that tube in the water again, it unrolled and reformed as the origami star.
The researchers believe the material could help reduce waste in the fashion industry. They suggested it could be used for truly one-size-fits-all clothing that stretches to fit the wearer, or bras “whose cup size and shape can be customized every day.” Consumers could save as well if they don’t have to replace stretched-out clothes quite so often.
“This two-step process of 3D printing the material and then setting its permanent shapes allows for the fabrication of really complex shapes with structural features down to the micron level,” Luca Cera, a SEAS postdoctoral fellow and first author of a paper on the material, said in a press release. “This makes the material suitable for a vast range of applications from textile to tissue engineering.”
