A team of engineers at the University of Colorado at Boulder say that they have successfully added a fourth dimension to their printing technology, opening up exciting possibilities for the creation and use of adaptive, composite materials in manufacturing, packaging, and biomedical applications.
The team at Boulder, in collaboration with others at the Singapore University of Technology and Design, developed and tested a method for 4D printing. The researchers incorporated "shape memory" polymer fibers into the composite materials used in traditional 3D printing, which results in the production of an object fixed in one shape that can later be changed to take on a new shape, they said. The programmed action of the shape memory fibers creates time dependence of the configuration, giving it the 4D aspect.
The 4D printing concept, which allows materials to “self-assemble” into 3D structures, was initially proposed by Massachusetts Institute of Technology faculty member Skylar Tibbits in April. Tibbits and his team combined a strand of plastic with a layer made out of “smart” material that could self-assemble in water.
The Boulder engineers advanced this concept by creating composite materials that can morph into several different, complicated shapes based on a different physical mechanism. The secret of using shape memory polymer fibers to generate desired shape changes of the composite material is how the architecture of the fibers is designed, including their location, orientation, and other factors, they explained.
They demonstrated that the orientation and location of the fibers within the composite determines the degree of shape memory effects like folding, curling, stretching, or twisting. The researchers also showed the ability to control those effects by heating or cooling the composite material.
As 3D printing technology matures with more printable materials and higher resolution at larger scales, the research should help provide a new approach to creating reversible or tunable 3D surfaces and solids.
