As if a brain-like processing chip weren't bad enough news for us humans, this week's edition of Science also describes a robot that, after being laid out as a flat sheet, can fold itself into the appropriate shape to take its on-board electronics for a walk.

Why would we possibly want self-assembling, flat-packed electronics of this kind? The authors of the Science paper, who are part of a Harvard/MIT collaboration, offer two reasons. First, it's much easier to assemble something as a planar surface. With the right layers in place, it's simple to cut them into the appropriate shapes and then embed the electronics where they're needed, since there's no awkward internal spaces to deal with. The second reason is that it's easy to transport things when they're shaped like a sheet. Since the devices can assemble themselves, they can be shipped to any destination and used without any hassle or high-level technical knowledge.

Of course, having a good idea and actually knowing how to create a self-assembling device are two different things. Fortunately, the ability to construct elaborate three-dimensional items from a flat sheet is a solved problem, thanks to origami. Software like Origamizer can even determine how to cut and fold a sheet in order to produce a specified three-dimensional structure.

Generating the force required to fold the sheet involved the use of something called a shape-memory composite, which can be locked into one conformation while still retaining a "memory" of a second one; given the right stimulus, the material will shift to the second shape. For this particular work, the team relied on pre-stretched polystyrene, which will change conformations when heated to 100 degrees Celsius.

Their robot consists of a flexible circuitry core sandwiched between two sheets of paper, which were in turn sandwiched between sheets of pre-stretched polystyrene. The outline of the device was then cut through all of the layers. At the joints, the electronics layer contained resistors that could provide localized heating, triggering the folding process nearby. Gaps were cut in the paper to encourage folding at specific locations, with the size of the gap setting limits on how far the material folded (e.g., a small gap might allow a fold with an angle of 30 degrees, while a larger one could allow a fold of 120 degrees).

Once everything was set, some simple circuitry was inserted on top of the sheet, along with batteries to power the device, and two motors were added. The circuitry both controlled the folding process—folds have to occur in a specific order to ensure production of the correct three-dimensional shape—and the robot's walk.

To actually propel the robot, the folding created what's termed an eight-bar linkage. Wikipedia's entry for a four-bar linkage has an animated GIF that shows how it can be used to generate motion; the eight-bar linkage simply extended the system so that each motor propelled two legs rather than one.

The authors argue that the whole thing could be assembled in an automated fashion—think laser cutting and robotic placement of the motors, battery, and control hardware. But for the purposes of this paper, they simply put everything together by hand, a process that took two hours. Once everything was in place, the robot assembled itself in four and a half minutes.

Some of the time, at least. The authors report on just three examples and in two of them, a single hinge (out of 28) failed. The video seen above shows the single working example of one of these self-folding robots that had worked when the paper was submitted (it's possible the team has built more since). But the successful build worked in every regard. Once folded up, it shuffled off under its on-board programming, moving at a clip of 5.4 centimeters a second—a bit under half its body length.

Even if it were equipped with one of IBM's new neuron chips, a five-inch long robot composed mostly of paper probably doesn't pose much of a threat to humanity. (Unless that's what it wants us to think.) However, the authors indicate that paper was just convenient for a proof-of-principle—there's no reason that either the paper or the polystyrene could be swapped out for something more robust. And given the right materials, there's no reason this approach couldn't scale to something larger. The authors suggest that there may be a time when emergency shelters aren't so much built as flattened out and plugged in, after which they self-assemble.

Science, 2014. DOI: 10.1126/science.1252610 (About DOIs).