Could we one day print self-assembly robots?

Along with the Industrial Internet, 3D printing is poised to transform manufacturing. According to technology research firm Canalys, the market could reach US$16.2bn by 2018. As companies like Carbon3D work to bring the process up to industrial speeds, scientists are already exploring the next evolution of the technology: 4D printing.

4D printing manufactures objects that can transform over time. MIT mathematician Dan Raviv and his colleagues demonstrated the concept in 2014 with products that could change shape after they were printed.

Whereas traditional 3D printing uses mechanically passive materials such as plastic or metal, 4D printing relies on active materials to create dynamic structures. Mr Raviv’s research, for example, combined a rigid plastic with a material that doubles in volume when immersed in water. This enables the objects to stretch and fold into shapes based on designs developed with the help of Autodesk, a California-based 3D design company. (The precise formula of the water-absorbent material, developed by Stratasys, remains a trade secret.)

How the active materials react to factors like heat and pressure informs the shapes that can be created. Mr Raviv imagines medical implants that can change shape and function in response to conditions in the body or clothing and footwear that can optimise their performance by sensing the environment.

The ultimate goal, of course, is to print multiple active materials concurrently to manufacture complex parts such as circuits, actuators, batteries and sensors integrated together into sophisticated devices. “Our lab’s goal is to print a robot that would walk out of the printer,” says Hod Lipson, director of Cornell University’s Creative Machines Lab.

He is not the only one with that objective. Last year, at Harvard University, Sam Felton and his colleagues invented a droid that can transform from a sheet into motorised origami. The robot consisted of paper coated with a plastic that shrank when heated as well as motors, batteries, microchips and hinges designed to fold at specific angles. After the electronics heat the plastic, the machine folds itself and can then walk once the system has cooled.

In the future, these technologies could enable printed machines to be shipped in flat boxes and to self-assemble once the box is opened. Another possibility, according to MIT computer scientist Daniela Rus, could involve customers selecting a robot from a library of customisable designs and then getting the printed result from a 24-hour store.

The most difficult part for now, says Mr Lipson, is to print the circuits that serve as the brains and the actuators that act as the muscles. Research on new active materials is also needed. “We will need to find ways to print it all together and to create a new generation of design tools that will allow us to explore this new design space. In my opinion, this will require AI tools, since the human ability to imagine the possibilities is too limited,” he notes.

This article is published in collaboration with GE Look Ahead. Publication does not imply endorsement of views by the World Economic Forum.

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Author: Charles Q. Choi writes for GE Look Ahead.

Image: A figurine is printed by Aurora’s 3D printer F1 during the 2014 Computex exhibition at the TWTC Nangang exhibition hall.  REUTERS/Pichi Chuang