In 4D printing, one more dimension is added: time. After an object is 3D printed, it changes its shape in one way or another. Researchers at the Georgia Institute of Technology in Atlanta, the Xi’an Jiaotong University, and the Singapore University of Technology and Design developed a new type of 4D printed material that can change its shape when exposed to heat.

Previously, a material had to be trained and programmed after it had been 3D printed to morph. Researchers had to heat it up, stretching it out, and letting it cool down again for the material to learn the new form. The new material, however, has already been programmed in the printer.

The new material consists of two materials that are carefully combined in the 3D printed structure to create the desired shape shifting effect. A soft polymer holds the energy that drives the change. However, in its cool state, this material is contained by another, glass-like, stiff material. When the material heats up, though, the outer material softens, allowing for the soft polymer to take over. The material is designed to remember the second shape and default to it when it is heated.

The structure can be shaped into any form, which it will keep until it is heated again. Then it transforms back to the second shape.

The tested material had to be heated to 50 degrees Celsius (122 degrees Fahrenheit) before it changed shape, but the outer material can be engineered so that it softens at a different temperature.

The material could be used for example in biomedical devices such as stents, or electronic components.

Image: Georgia Institute of Technology in Atlanta / Xi’an Jiaotong University / Singapore University of Technology and Design