With everything from fully functioning 3D-printed homes and massive structures like 3D-printed steel bridges entering the realm of engineering capabilities, new and dynamic design concepts are emerging every day. Perhaps the best part of all this is that the 2D to 3D transition has been enthusiastically welcomed by many people in a number of industries and fields.

Just as we are adjusting to this new reality, however, 4D is emerging on the horizon as well. A team of researchers from City University of Hong Kong (CityU) have developed a 4D printing method for ceramics, the first of its kind in the world.

3D printing with a next step

As the name implies, it takes the 3D printing model and adds a crucial step which involves morphing the shape of the object. The result is a process that combines a production followed by a real-time, interactive editing process.

In order to achieve their desired effects, the team developed an ink which contains both ceramic nanoparticles and elastic polymers. When heat is applied, the special ink is able to stretch three times greater than its starting length--the compressive strength density of the material measures47 MPa on a 1.6 g cm-3 microlattice.

As one would imagine, the innovative two-step process, which took two years to develop, involved a significant amount of trial and error. "From making the ink to developing the printing system, we tried many times and different methods. Like squeezing icing on a cake, there are a lot of factors that can affect the outcome, ranging from the type of cream and the size of the nozzle, to the speed and force of squeezing, and the temperature," said Professor Lu Jian, who is also the Chair Professor of the CityU's Mechanical Engineering Department, led the research team.

Exciting applications ahead

The intricate process could lead to a number of exciting new research projects and ventures. Professor Lu spoke about the enormous potential of 4D printing in the future: “With the versatile shape-morphing capability of the printed ceramic precursors, its application can be huge.”

“One promising application is electronics. Ceramic materials have much better performance in transmitting electromagnetic signals than metallic materials. With the arrival of 5G networks, ceramic products will play a more important role in the manufacture of electronic products," further explained Lu.

The professor also believes the material's artistic nature and potential to be moulded into complex shapes could see it put to use in custom-made mobile phone backplates. Even more impressively, argued Lu, ceramic's tolerance for high temperatures may one day see its application as a propulsion component in the aerospace field.

The work of this committed team of researchers demonstrates that although perhaps you can not reinvent the wheel, you can dramatically change the process behind how the wheel itself is made.

Details about the innovative work were shared in a paper, titled "Origami and 4D printing of elastomer-derived ceramic structures", which was published in the Advanced Sciences journal this week.