These tiny objects made with 3D printers can dramatically expand when exposed to heat. A team at the Georgia Institute of Technology has created these pair of compact, unfurling structures. These structures could pave the way for innovations in biomedical devices or space exploration, where payloads can cost tens of thousands of dollars per pound. The researchers feel that beyond space exploration, these new 4D structures might be used in creating shape-shifting robots in the coming future.

These 3D objects use ‘tensegrity’ which is a structural system of floating rods in compression and cables in continuous tension. Researchers have crafted the rods and cables which are called ‘struts,’ from shape memory polymers that unfold when heated. Tensegrity structures are extremely lightweight while also being very strong. The goal is to find a way to deploy a large object that initially takes up little space.

This method is called ‘4D printing’, where a 3D-printed structure changes shape after a print. The fourth dimension is time, in this case, as it expands “in time”. The researchers made the struts from 3D printers. To allow the struts to be temporarily folded flat, the team designed the struts to be hollow, with a narrow opening spanning the length of the tubes. Attachment points at the end of each strut connect the tubes to a network of elastic cables, which were also made with 3D printers. Next, the struts were heated to 65 degrees Celsius and once they cooled, the structures retained their temporary shape.