With the help of a special ink, researchers have created 3D printed flowers that change shape when they’re immersed in water, mimicking a plant’s ability to respond to its environment.

They call the method 4D printing, due to the addition of the fourth dimension of time. Although researchers have achieved 4D printing in the past, this team is unique in printing objects in one step using a single material.

Watch the process of printing the flower-shaped objects:

“We were inspired by plants,” Sydney Gladman, co-lead author of the study, told Popular Science. “Pinecones, when they are wet, they’re closed up, protecting the seed, but when they fall off the tree, they dry out and open up, exposing the seed… all we had to do was design an ink that could express this behavior.”

They did so by creating an ink made from hydrogel and cellulose, a major component of the cell walls in many plants. The hydrogel swells when submerged in water, which allows the printed flowers to move and change shape. The researchers also developed a mathematical model that predicts the way the printed flowers will move once submerged. This allows them to control the shape the object takes on by manipulating the pattern of cellulose fibers within the gel.

“Just by changing the code that we use to print the structures, that will change what types of geometry we achieve once it swells in water,” says Gladman.

Eventually, it could be possible to 3D print a material that responds not only to water, but also to light and temperature, Gladman says. This research could eventually be of use in the development of biomedical devices, smart textiles, and transformable tissue engineering.

The process begins with printing the object from ink containing hydrogel and cellulose. This printed flower was shaped after an orchid. Wyss Institute at Harvard University
The printed flower changes shape over time after being immersed in water. Wyss Institute at Harvard University
This printed flower was modeled after a calla lily. Wyss Institute at Harvard University