Forget 3D Printing, What the Heck Is 4D Printing?

Summary

• 4D printing is real, happening now, and has the potential to shape the world.
• Self-assembly in 4D printing uses materials responding to external stimuli.
• A regular 3D printer can be used to create 4D objects with proper design phase.

Printing in “4D” might sound like something cooked up for a sci-fi novel, but it’s actually a real object printing technique that builds on what’s already possible with current 3D printers in mind-bending ways.

4D printing is real, happening right now, and it just might have the potential to change the world.

4D Printing Is All About Self-Assembly

So what’s the 4th-dimension we’re talking about here? You’ve probably guessed that it’s time. The idea is that the 3D-printed object can change it’s shape and self-assemble into a different final form after being 3D-printed.

This idea really got its start at MIT, at the Self-assembly lab established by Skylar Tibbits. 3D printing and modeling giants Stratasys and AutoDesk had their hand in it as well.

The idea is that the 3D-printed object has both rigid and flexible, expandable components. The expandable material responds to external stimuli after the object is printed. Tibbets presented this idea in a TED Talk over a decade ago, but it’s still fascinating, and the technology to do it effectively is now much more advanced than it was back then.

Self-assembling structures like these are part of the larger category of programmable matter, and when you think about it, the most complex system we know—life—is built on the self-assembly of simpler structures. This is how proteins work, and, of course, animals start out as a single embryo, that divides, and then repeatedly folds into the different body structures.

Think of origami, where a single flat sheet of paper can be formed into an infinite number of complex structures simply through folding. If you can grok that, you’ll realize how important 4D printing will be.

4D Printing Happens on a 3D Printer

The best part is that you don’t need a special “4D” printer to make 4D objects. A multi-material 3D printer can already make these objects, as long as it can print the required materials.

The real genius here is in the design phase. Designers of 4D objects use special software to design and plan how to go from a regular 3D-printed object to a complex 4D one. Maybe even more importantly, many of these objects aren’t designed to self-assemble once, but to change their configuration as needed. A major example Tibbets has cited over the years is water pipes that can change their size in response to the needs of the supply line. In much the same way, your veins can change their diameter to regulate the pressure and flow of blood through your body.

Software simulation is the real key here though. By using computer simulations, designers can really nail down exactly how to print something, so that it self-assembles in just the right way when you add energy.

Energy and Matter Activate its Final Form

A 4D print isn’t complete when it leaves the printer—it’s latent. It still needs an activation event. That could be:

• Heat: Some materials expand or contract dramatically at specific temperatures.
• Moisture: Hydrogels swell or change shape when exposed to water.
• Light: UV or infrared light can trigger chemical changes in the material.
• Magnetic fields: Magnetically responsive materials can shift in complex ways.

It doesn’t have to be limited to these either. Some of the self-assembling structures Tibbets showed off in that original TED Talk reacted to kinetic energy as well. In other words, if you shake them, they begin self-assembling.

There are also new metamaterials in development all the time, such as artifical muscle-like fibers that contract when electricity is applied. If you could print those materials, they could be included in the design of a 4D printed object.

Can You 4D Print at Home?

It’s technically possible for us to do 4D printing at home using our 3D printers. If your printer can print the right materials, and the design is sound,there’s nothing stopping current 3D-printing hobbyists from attempting 4D printing.

In practice, the materials you need aren’t readily available, your printer probably won’t print it without modification, and actually designing these objects (the hardest part) won’t be something just anyone can do.

That said, in 2023 Teaching Tech attempted to make a basic 4D print at home using existing filaments and printers.

After a lot of head scratching and trial and error, he was able to pull it off. So, in principle, we aren’t miles away from 4D designs that are printable at home. Of course, technically there are some prints that only need a little kinetic energy from you to change shape after printing, but strictly speaking, that’s not self-assembly!