Researchers have devised all different kind of materials for different applications ranging from electronics to tissue engineering, that respond to different stimuli such as heat or light with changing their shape in a complex pattern. This might be reversible or not, depending on the different applications, but mostly it is the idea to crate a structure that is otherwise not possible to manufacture. 

A team of researchers from Harvard (USA) have developed now a simpler method to achieve complex structures using thereby 3D printing technology.

The main achievement lies thereby in the developed viscoelastic ink, which is composed of cellulose fibrils embedded in a hydrogel.
The fibrils will align themselves parallel to the extruded hydrogel filament when pressed through the printer nozzle due to shear forces.
Immersed in water the filament will swell. So far so good. But now the second development takes the lead: The extruded filament is laid out on a patterned surface. This causes the structure to buckle up because of surface forces. Choosing now a special pattern on leads to different three-dimensional structures. The latter can be predicted mathematically rendering the procedure an elegant method to create any kind of three-dimensional structured using 3D print technology.

The work has been published online recently in the leading journal Nature Materials (doi: 10.1038/NMAT4544).