The beginning of a new year often prompts thoughts of the more distant future. In the context of 3D printing, 4D printing could be a part of this distant future (at least a decade away). In 4D the 3 dimensions we all know – X, Y, and Z – are joined by time, the 4th dimension. This means that items change over time rather than remaining static. 4D printing is still deep in the research phase and we don’t think that we will see commercial 4D printed items in 2019, but Gartner believes by 2023 $300 million will be invested into 4D printing. With that in mind, we gathered a few examples of this cool and exciting capability.
4D printing encompasses many disciplines: engineering, physics, chemistry, materials science and CAD capabilities are all needed in order to design 4D printed items and their actions and reactions (which cause a 3D printed object to transform). The transformation can be induced by a number of factors: the transformation can be triggered by environmental elements such as liquid, moisture, temperature, light, each triggering a different kind of “magic”. At the Engineering Design and Computing Laboratory at ETH Zurich, they are working on 4D printed tetrahedrons (below). The tetrahedrons, printed in a flat form, react to warm water and shift to form a predetermined structure. Another heat triggered example demonstrated the possibilities in creating structures that expand and self-assemble. In this latter example, the idea is that the heat triggered reaction is permanent, though in some 4D printed items when the trigger is removed the action is reversed.
A wooden material 3D printed by MIT Self Assembly Lab combines wood dust and polymers which react to moisture causing the material to curve (above). In the UK, the University of Bristol and the University of Bath, collaborated on creating a cellulose-based ink for 3D printing, the printed object resembles the structure of a pine cone and when placed in water it morphs and contracts similar to the growth of a pine cone in nature. All of these ideas can, for example, be applied to transporting flatpacks to remote locations and then having the items self-assemble when triggered. Yet I have to wonder, if the triggers are environmental how do you control when and where the transformation occurs?
Another group of triggers explored in 4D printing is chemical reactions. Here I can imagine the when and where are more easily controlled. A couple of examples for chemically induced changes can be seen in medical studies. One is a 4D bioprinting technique that has the potential to create smart structures for nerve regeneration. The research conducted at George Washington University used Soybean Oil Epoxidized Acrylate (SOEA) to 3D print a flat star shape. When washed with ethanol the structure transforms creating a “blooming movement”. A few other medical researchers are 3D printing living cells, the 4th dimension provides their ability to grow and become a functional tissue, and the triggers used are environments that imitate body conditions (below 4D printed placenta disk). This technique is applicable in medical studies where the 4D printed tissue can substitute human or animal tissue.
Expanding and Contracting
In both cases of transformations, whether it’s natural conditions or chemical solvents, 3D printing provides the basis. 3D printing enables the creation of different densities within the same object, in a weave-like pattern or in various consistencies. The variations in the material structure react differently to the same stimuli and those opposite forces create the shape-shifting. Opposite forces can also be triggered by the geometry itself as in the ceramic ink developed by the City University of Hong Kong. Here the ink, combining polymers and ceramic nanoparticles, can be stretched and its elastic energy creates the transformation: when the tension is released the shape transforms. The final step is heat treatment which actually turns the precursors into ceramics. Due to the material’s high conductivity and tolerance to high temperature the research team believes the 4D printed ceramic material can be applied in electronic devices as well as aerospace applications.
Out of Thin Air
Self-assembling structures can also be created by combining 3D printing with air, as in inflatables. I’m not sure this really falls into the category of 4D printing, but it does combine a 3D printed form that changes after the production process. MIT’s Self-Assembly Lab is working together with BMW on 3D printed forms that are created using Liquid Printed Pneumatics and change shape when filled with air (above and up top). This technique can be applied in the redesign of airbags or customizable car interiors. The printing method is interesting in itself: it takes place in a vat of silicone, the silicone serves as a support structure from which the 3D printed object can be easily removed without applying unnecessary force and keeping it intact. Another project using air to add a dimension of movement to a 3D printed object comes from Victoria University of Wellington, New Zealand, where Master’s student Nicole Hone, designed what she describes as 4D printed interactive plants. Here the use might be less practical but it does create movement and transformation of inanimate objects, which can be used in animation videos (below).
What’s interesting beyond the “magical effect” of 4D printing is the understanding that things naturally change over time and this is a factor to not only consider but something that can be planned and controlled. When it comes to reaching the status of a commercialized technology, 4D printing still has a long way to go. Still, innovation relies on us looking forward, imagining what could be beyond just the short term plan. Let’s check back in 2023 and see where 4D printing will be :).
Have you encountered 4D printing experiments or applications? Tell us about it in the comments below. For more insights and information follow us on LinkedIn or subscribe to our newsletter for weekly updates.