In the April issue of Metropolis Magazine an article titled “Source Material” (previously mentioned here) discusses a concept they call 4D printing. Of course the first question that comes to mind is- how can an object have a FOURTH dimension when the world only exists in 3 dimensions? Well, I hate to be the bearer of bad news, but we live in a four dimensional world. In a 3 dimensional world, if i were going to make an appointment to meet you, i would specify 3 dimensions: how far North-South (i.e. 34th st), East-West (6th Avenue) and the elevation (third floor) also known as the X Y and Z axes. But in the real world, this would make for pretty lousy planning. I’ve told you where to meet me, but I haven’t told you WHEN. The fourth dimension of our universe is time.
So 4D printing involves creating an object that changes in time based on some external stimulus. It sounds very complex but it’s surprisingly simple when you wrap your head around it. For instance, in a simple way, any product that has moving parts involves the fourth dimension of design. So in a way 4D printing has been with us as along as 3D printing in the form of printed hinges and flexible materials. But I guess you could call this “passive 4D” because the product only changes with time in a direct way when an agent (i.e. a person) acts upon it.
For instance, my nylon earring designs are all printed as a single unit from powdered nylon. Each individual shape is printed interlocking with its neighbors but not touching. They are supported and kept separate during the printing process by unmelted nylon powder. When the print is complete, the series of solid interlocking forms is removed from the powder and each link falls to rest on its neighbor like a chain.
The next step in “passive” 4D printing came from the ever-brilliant minds of Jessica Rosenkrantz and Jesse Louis-Rosenberg over at Nervous System. In November 2013 the team introduced a system and accompanying wearable collection called Kinematics which facilitates the design of large 3D printable items that fold and compress to be printable in a much smaller area than the size of the object would imply . This is achieved by designing a product made from smaller hinged panels that enable the part to unfold after printing.
“Kinematics is a system for 4D printing that creates complex, foldable forms composed of articulated modules. The system provides a way to turn any three-dimensional shape into a flexible structure using 3D printing. Kinematics combines computational geometry techniques with rigid body physics and customization. Practically, Kinematics allows us to take large objects and compress them down for 3D printing through simulation. It also enables the production of intricately patterned wearables that conform flexibly to the body.” [Nervous System Blog, 11/26/13]
It’s a lot like when you wad up a t-shirt into a ball– it occupies the same amount of space as it does when you lay it out flat, but it fits into a much smaller box. This is the first step in 4D printing– objects that move, bend, and fold.
But the Metropolis article introduced me to a concept that I’m going to call “responsive” or “active” 4D printing. This seriously blew my mind when i heard it, but when i really started to think about it I found analogs in nature, as usual. Apparently Skylar Tibbits of SJET.US is trying “to create active printed structures that can transform and reconfigure—change shape, appearance, and properties. Therefore, they become actuators, sensors, and physical computing devices” (Metropolis Magazine, April 2014). In other words, these would be objects that can change based on outside stimulus more intricate than simply a hand pushing a hinge closed. These objects involve the layering of different materials in different configurations that would react differently in different environments causing a change based not on an active outside influence, but on, for instance, a change in humidity, temperature or other environmental factor.
Lets look at some non-printed examples. Lets say you made a striped blanket by cutting strips of two different fabrics and sewing them back together by alternating the two materials: one red and one blue. But you failed to consider that, while both materials are made of cotton, the red material has been pre-shrunk and the blue has not. What happens when you wash and dry your striped blanket? The red panels stay the same size, but the blue panels now shrink, causing the seams and the red panels to gather, and your blanket is no longer as big as it was. It has changed in the fourth dimension, not just the positions of the parts relative to one another, not just because you pushed or pulled on it, the internal structure of one part has changed (shrunk), causing a change in the overall shape of the object.
The second example will be familiar to anyone with curly hair. Curly hair changes shape based on the ambient humidity. We usually call it frizz and get annoyed, but imagine if this idea could be used to tell a humidifier when to turn on or off or when the garden sprinklers should turn on. This would allow a single 3D printed object to take the place of complex electronics.
The article includes this compelling series of photographs of a 3D printed item “self-assembling” in water. If you can imprint shrinkage and flexibility on a material that is dependent upon an external factor you could create truly responsive materials. Imagine a tile which, when wet, changes shape to channel the water to a specific place and provide traction but becomes flat and easy to clean when dry. Or maybe you could print a flat sheet (easy to transport, stack, etc.) that turns into a lounge chair when you put it into the sun. Think that sounds like science fiction? Well, yeah, but it’s about to be science fact. Witness:
Responsive or “active” 4D printing is without a doubt the future of manufacturing. Once readily available machines are able to apply multiple materials to a single print, which is bound to happen within the next few years, the next wave of innovation will go beyond experimenting with different materials to experimenting with how the different materials can influence each other, and the possibilities will suddenly grow exponentially.