These 3D printed materials can change shape

Researchers at Rice University in the United States have developed a new 4D printing technique. Thanks to a liquid crystal elastomer and ultraviolet rays, they simplified the creation of soft robots or medical implants, capable of changing shape.

4D printing relies on a 3D printer to create objects capable of changing shape. So far, one of the main weaknesses has been that the states are predefined, calculated in advance taking into account the properties of the materials and the way the object is printed. Researchers at Rice University have succeeded in creating a new 4D printing technique that allows you to create a second shape by manipulating the object before fixing it with light .

The technique is based on the use of a polymer which integrates mutually exclusive chemical bonds . Researchers print a precursor solution of liquid crystal elastomer in a catalyst bath to create the initial structure. The next step is to deform the object by mechanical manipulation. This second state is then fixed by means of ultraviolet rays .

Heating or cooling the structure changes its shape

The object obtained can then switch between the two forms thanks to heat variations , but also an electric current or a mechanical stress. This 4D printing technique therefore makes it possible to create polymorphic materials which could be used in the field of soft robotics , or even for medical implants which adapt to the body.

At present, this technique cannot print structures that are not supported, because of the material which is too soft. The team is therefore working on a printing system that uses scaffolding to create more complex shapes. Researchers thus imagine creating soft robots that swim like a jellyfish or jump like a grasshopper .