"Squishy" robots, capable of being transferred into nearly any shape, may be possible with the development of a new material. These "phase-changing" robots will be able to convert from a rigid to a flexible structure and back again.
MIT researchers developed the low-cost material from foam and wax. Development of the substance could lead to robots able to withstand severe blows, and then flow under a door, like the T-1000 robot from Terminator 2.
"[P]reliminary studies indicate that the composites exhibit self-healing properties, in which heating between loading cycles can mend wax that has been plastically deformed, for example, by cracking or delaminating from the foam," researchers wrote in an article announcing their discovery.
Small robotic devices injected into the bloodstream of a person could journey around the body of a patient, repairing damage without harming healthy systems. This ability could be used to investigate the wreckage of buildings after disasters, searching for victims. The idea is similar to the behavior of octopuses, which can squeeze through tight spots.
The Defense Advanced Research Projects Agency (DARPA) is interested in developing squishy robots to travel through buildings. The advantage of such as design is that such robots could combine the ability to squeeze into areas with the rigidity need to move objects.
"You can't just create a bowl of Jell-O, because if the Jell-O has to manipulate an object, it would simply deform without applying significant pressure to the thing it was trying to move," Anette Hosoi, professor of mechanical engineering and applied mathematics at MIT, said.
The team coated a foam structure with wax. Foam is able to be compressed to a fraction of its normal size and later spring back into shape. Wax used on the material normally creates a rigid structure, but a small amount of heating causes the polymer to soften. This is accomplished by applying an electrical current through wires implanted in the wax. Heating causes the material to become pliable, and when current is shut off, the wax returns to its normal rigid structure. Longer periods of warming melt enough wax to repair most small cracks and faults.
In a second round of the experiment, Hosoi and her team created a second version of the structure on a 3D printer. This allowed the team to carefully control dimensions in the test product. This allowed researchers to take more consistent data than they could gather from the handmade structure.
Development of the phase-changing material was detailed in the journal Macromolecular Materials and Engineering.