Researchers from the Singapore University of Technology and Design and the Georgia Institute of Technology developed a 4D printing technology that makes complex self-folding structures possible.
The technology, described in a study published in the journal Scientific Reports on Sept. 8, could be used to create three-dimensional structures that can fold themselves sequentially from components and rolled into a tube or flattened for shipment.
Potential applications for the technology abound and could pave the way for the creation of vehicles that can shift shape when necessary.
The researchers used components that are capable of responding to stimuli such as moisture, light or temperature in a precisely-timed manner to create deployable medical devices, space structures, toys, robots and other structures.
The team used shape memory polymers, or SMPs, that can remember one shape and transform to another once uniform heat is applied.
"Shape memory polymers are smart materials that can recover their permanent shapes from one (or sometimes multiple) programmed temporary shape(s) when an appropriate stimulus is applied," the researchers wrote. "Since this type of smart materials has the potential to sense environmental changes and react accordingly in a predetermined sequence, they are promising candidates for spontaneous configuration-changing applications."
H. Jerry Qi, from the Georgia Institute of Technology, said that earlier efforts to create components that can sequentially change shape involved placing several heaters at particular regions in the component and controlling the on and off time of each of these heaters, a process that he described as complicated.
His team, however, has managed to find a work-around that makes it possible for them to utilize heat more easily - by exploiting the ability of different materials to control the rate of shape transformation through their molecular design.
The researchers demonstrated this approach using several examples, including a mechanism that can switch from a flat strip into a locked configuration with one end able to bend and thread itself through a keyhole.
The researchers envision a range of applications for this technology. An unmanned air vehicle, for instance, could change shape from one design that was intended for a cruise mission to another that was designed for a dive.
The technology could also make possible 3D components designed to be rolled up into tubes or fold flat for easy transportation and later transformed into their intended three-dimensional configuration.
