Using a set of smart shape-memory materials that each respond in a slightly different way to heat, researchers have demonstrated a four-dimensional printing technology that creates complex self-folding structures.
Developed by researchers at Georgia Tech and the Singapore University of Technology and Design (SUTD), the technology can produce 3-D structures that sequentially fold themselves from components that had been flat or rolled into a tube for shipment. Initiated by temperature, moisture, or light, the self-folding process can be precisely timed to create space components, deployable medical devices, toys, and other structures.
The researchers used shape memory polymers (SMPs) with the ability to remember one shape and change to another programmed shape upon the application of heat. The ability to create objects that change shape in a controlled sequence over time is enabled by printing multiple materials with different dynamic mechanical properties in prescribed patterns throughout a would-be 3-D object. When these components are then heated, each polymer responds by changing its shape at a different rate, following its own internal clock. By carefully planning these changes, 3-D objects can be programmed to self-assemble.
“Previous efforts to create sequential shape-changing components involved placing multiple heaters at specific regions in a component and then controlling the on-and-off time of individual heaters,” explained Jerry Qi, a professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. “We turned this approach around and used a spatially uniform temperature and then exploited the ability of different materials to internally control their rate of shape change through their molecular design.”
Published in the journal Scientific Reports, the research was funded by the U.S. Air Force Office of Scientific Research, the National Science Foundation, and the Singapore National Research Foundation.
Source: Georgia Tech