Self-assembling robots, created by 3-D printers, could become a reality in the near future. 

Daniela Rus, a professor of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology, led research in bakeable robots - mechanized beings that self-assemble when heated. 

Robots could be created on 3-D printers, and then exposed to a heat source. The sheets would then fold themselves into pre-determined shapes, shaping the robot. Production of these devices will require advances in at least a pair of fields - design of electronic components capable of self assembly, and computer control and design to manufacture the sheets. 

"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,'" Rus said.  

A pair of papers each examined how to create a 2-D shape capable of self-assembly and electronics capable of assembling themselves. 

Self-assembling resistors, capacitors and inductors were among the essential electronic components researchers designed. Designs for actuators and sensors that would act as muscles for the robots were also offered by the team. 

Sheets consist of a layer of polyvinyl chloride (PVC), sandwiched between two stiff sheets of polyester. The outer layers are scored with slits of varying widths. Heat causes the PVC to contract, which exerts force on the polyester sheets, closing the slits. Angles are ridges cut into the slits directs the folding into per-determined shapes. 

One example is a pair of slits cut into outer layers, with the top layer wider than the channel in the bottom sheet. Heat will contract the sheet until the bottom edges meet forming a hinge. As the sheet continues shrinking, it keeps being upwards, until the layers at the top make contact. One of the challenges in production is that the PVC shrinks in all directions at once, complicating the folding process. 

"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," Rus stated in a university press release. 

In the other paper for which Rus was a co-author, researchers investigated using polyester lined with aluminum to create foldable electronics. Creating accordion-like shapes with resistors in each fold changes electrical currents, forming a simple sensor. 

Actuators for the robots may be the only part of these robots that could not be entirely created on 3-D printers. Researchers say a pair of iron cylinders would be required to run the propulsion devices.