Engineers from MIT and Singapore University of Technology and Design (SUTD) are using light to print three-dimensional structures that “remember” their original shapes. Even after being stretched, twisted, and bent at extreme angles, the structures sprang back to their original forms within seconds of being heated to a certain temperature “sweet spot.”
The team printed a variety of structures, including coils, flowers, and the miniature Eiffel tower. These structures could be stretched to three times their original length without breaking. When they were exposed to heat within the range of 40 C to 180 C, they snapped back to their original shapes within seconds.
The process of 3-D printing shape-memory materials can also be thought of as 4-D printing, as the structures are designed to change over the fourth dimension — time.
The MIT’s new method not only enables 4-D printing at the micron-scale, but also suggests recipes to print shape-memory polymers that can be stretched 10 times larger than those printed by commercial 3-D printers. This will advance 4-D printing into a wide variety of practical applications, including biomedical devices, deployable aerospace structures, and shape-changing photovoltaic solar cells.
