4d printing, for those who don’t know, is a great evolution within 3D printing in which different types of materials are used that can react to the environment, meaning that projects can be created that change shape without anyone touching them, through external energy inputs or other environmental stimuli.
But what is 4D printing?
4D printing is an evolution within 3D printing. It is the creation of 3D printed objects that change after reacting with the environment and can bend, repair, assemble, disintegrate when they receive a certain external stimulus. They acquire a new form or functionality under the influence of external energy input, such as temperature, light or other environmental stimuli, and that, in short, can have “life of their own” by themselves.
This means that if you print a 3D object with a 3D printer, but do so with special materials and a design that takes them into account, you can create a product that reacts to different stimuli without you having to touch them. In addition to the shape, these objects can also change colour or size.
Although this will depend on the materials used, they will react in one way or another depending also on the type of stimulus they receive. Therefore, when designing and printing them in 3D, designers must also have thought about the specific material they want to use in the objects so that, after printing them, they will behave as expected.
In short, you can think of 4D printing as a functional form of 3D printing. Instead of printing simple physical structures, what is printed are objects that perform certain functions. It’s like incorporating a piece of code into the material, and once it’s activated it gets the object to do that which it’s programmed and designed to do.
What materials are used?
Today, the materials used for this type of printing are not as varied as when printing simply 3D objects. You have to understand that this is a fairly new technology and that it is still taking its first steps, so it still has a lot to evolve. Even so, it already has some different materials.
On the one hand you have the shape memory polymers (SMP), which are materials that memorize a macroscopic shape and hold it for a certain time, but then return to their original shape under the effect of heat or other stimuli, such as a magnetic field, an electric field, or water.
There are also liquid crystalline elastomers (LCE) which are materials containing heat-sensitive liquid crystals, the orientation of which can be controlled at will, so that objects printed with them can be made to take on a particular desired shape under the effect of temperature. In short, this is a material that can be programmed to move in a certain way depending on what you want to achieve.
Then there are the hydrogels, which are polymer chains made mainly of water. This material has focused its use in the medical sector because of its biocompatibility, and they are mainly used in light-curing processes.
Similarly, some objects used in 4D printing can use several materials at the same time, such as wood and the carbon added to shape memory polymers and hydrogels. In this way, you have parts of an object that are rigid and other parts that are in charge of moving.
What is 4D printing for?
As we told you at the beginning, 4D printing is still in its infancy, so the applications for which it is used are still being explored. This means that all of the uses we’ll tell you about below are potential uses that have not yet been applied, but which it is anticipated that 4D printing could have.
For example, imagine having pipes that are capable of automatically repairing themselves if they crack or break, or whose diameter may change in response to water flow or user demand. Piping systems could benefit greatly from this type of material.
We could also have furniture that can be mounted automatically. Imagine that you buy a piece of furniture that comes in a sheet, but if you apply light, heat or water to it it would have folds that are activated automatically, and like paper figures, they are capable of being folded neatly to form a table or a chair.
Another use for which it can serve is the creation of pieces that can be folded or expanded like the hook shown in the following image. This hook is heated and closed to try to grab an object. And all this is printed in one piece, without the need of external systems that make it move.
There is also the possibility of using 4D printing in large scale projects. For example, bridges, shelters and many other types of facilities could be built that automatically assemble or are capable of repairing themselves when bad weather causes damage.
It can also be useful in other sectors, such as medicine, by printing proteins that can reconfigure themselves. In addition, when making stents or other types of prostheses, these could be made to react to body heat, expanding to adapt to the patient for whom they were printed.
Another sector that could benefit from this technology could be the fashion sector, developing clothes capable of changing shape depending on the climate or body activity. Imagine footwear that could change shape when it detects you start running so that it is more comfortable and cushioned, or fabrics that are breathable but close themselves when they detect rain.
The possibilities are endless and this is a field of science that is just beginning to be experimented with. We will see what new advances technology surprises us with in this area in the coming years.