At this year’s IEEE International Conference on Robotics and Automation, Daniela Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT and collaborators at at the University of Zurich and the University of Tokyo introduced the promise of 2D printable robotic components that fold into three-dimensional configurations when heated. One paper describes taking the digital specification of a three dimensional shape and generates the two dimensional patterns to reproduce it through self-folding plastic. The other paper looks at building electrical components from self-folding, laser-cut materials. In this exciting development the researchers show designs for resistors, inductors, capacitors, sensors and actuators.
Some are calling it, unsurprisingly, 3D printing. It’s not. These components are 2D printed. That said, self-assembling 2D printed robots are an awesome idea. So, let’s have a look at this interesting new development, then consider what 3D printing is, and have a think about what is really going on here?
Rus said: “We have this big dream of the hardware compiler, where you can specify, ‘I want a robot that will play with my cat,’ or ‘I want a robot that will clean the floor,’ and from this high-level specification, you actually generate a working device. So far, we have tackled some sub-problems in the space, and one of the sub-problems is this end-to-end system where you have a picture, and at the other end, you have an object that realizes that picture. And the same mathematical models and principles that we use in this pipeline we also use to create these folded electronics.”
This process works by sandwiching a sheet of PVC between two films of a rigid polyester riddled with slits of different widths. When heated the PVC contracts and the slits close. Where the edges of the polyester film press up against each otherthey cause a deformation in the plastic. The process is, inevitably, more complex than it sounds. Rus said: “You’re doing this really complicated global control that moves every edge in the system at the same time. You want to design those edges in such a way that the result of composing all these motions, which actually interfere with each other, leads to the correct geometric structure.”
The concept is cool and wouldn’t earn a mention just to set the record straight for your benefit — the regular reader of 3D Printing Industry can likely discern that this is not 3D printing for themselves. The interesting quality of this robot’s design is that it self-assembles when the 2D-printed net is exposed to heat. 4D printing is so called because it adds the forth dimension of time, whereby materials chance their constituent shape after being printed by changing its properties – via heat, saturation by a liquid, or any other means. I find ‘4D printing’ a slightly strange term in itself. But it is now an established popular culture definition, so let’s go with it for my point here.
We could suggest that a 2D net that changes through time in reaction to a stimuli is indeed a kind of ‘3D printing,’ but it’s a different kind of ‘3D print: x and y axis printing of a material then a transition through the dimension of time. The z axis – bearing in mind the very blatant fact that 3D printing is called just that in popular culture because of also moving in the z axis: I would suggest that the term is a relative one, which required 2D printing to be thought of as ‘printing,’ then the ‘remarkable’ aspect that grabbed mass attention was printing in the third dimension, the z axis. The unexpected, the novel, garners attention.
Of course, those who have being reading more than a few articles about 3D printing will know that the official term derives from the original additive manufacturing process. It is a name for one of a number of additive manufacturing processes, that has become a generic term for all of them. x and y axis printing of a material then a transition through the dimension of time in reaction to a stimuli, is not what additive manufacturing is. There is nothing additive about the method of manufacturing of this 2D net. So, simply, this is not 3D printing.
This is important because understanding 3D printing is a leap of imagination for the majority of people, insomuch as my experience of explaining the processes to the uninitiated suggests. So, blurring the boundaries of definition is merely going to water down understanding and put the actual technology out of focus. Last year a survey in the U.S. found that a significant proportion of people questioned believed that additive manufacturing is a bad thing. Why?
The association between the term ‘additive’ and food additives, which receives regular negative news reports regarding the health problems that many cause. Clearly then, as such terms are already confused in the minds of the mass population whose daily lives do not touch 3D printing at all, clear definitions are pertinent. As is using them correctly. It’s not for me to decide what gets called 3D printing and what doesn’t. I can only share my opinion. And I’m certainly interested to hear yours: please do comment in the comments section below. Ultimately industry standards regulate the correct terminology, as of course they should. But the media, and thus popular culture, often exist independent of established technical prose. And in the case of ‘additive manufacturing’ and ‘3D printing,’ this is certainly true – a language development which is happening now, as we speak.
