A lattice created by a multi-material 3-D printer at Georgia Institute of Technology that can permanently expand to eight times its original width. (Rob Felt)

Researchers from Georgia Institute of Technology, the Singapore University of Technology and Design (SUTD) and Xi’an Jiaotong Universtiy in China have teamed up to invent a new 3-D printing method which creates objects that can transform into different shapes when exposed to heat. The objects are printed with layers of shape memory polymers, and each layer is designed to respond differently.

This new development expands on past work that this team had done using smart shape memory polymers. These polymers are able to remember one shape and change to another when heat is applied.

"This new approach significantly simplifies and increases the potential of 4-D printing by incorporating the mechanical programming post-processing step directly into the 3-D printing process," said Jerry Qi, a professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. "This allows high-resolution 3-D printed components to be designed by computer simulation, 3-D printed, and then directly and rapidly transformed into new permanent configurations by simply heating. The approach can achieve printing time and material savings up to 90 percent, while completely eliminating time-consuming mechanical programming from the design and manufacturing workflow,".

The new 4-D objects could enable a range of new product features. This would allow objects to be stacked flat or rolled for shipping and then expanded once in use. Eventually, the technology could make components respond to other stimuli like moisture or light. If timed correctly, this could be used to create space structures, deployable medical devices, robots, and toys.

The research was printed on April 12 in the journal Science Advances. The work is funded by the U.S. Air Force Office of Scientific Research, the U.S. National Science Foundation, and the Singapore National Research Foundation through the SUTD DManD Centre.