Primer behaved something like a crab in the lab, scuttling around on a surface toward its exoskeleton. It’s a magnetic robot driven by an external electromagnetic field — similar to how a magnet will move another magnet when held close to it. Miyashita said that another source of power could propel Primer or even replace it as an engine, be it an electric motor, a protein, or a cell.
The exoskeletons are flat pieces of laminated polyester or polyvinyl chloride film —plastic, basically — and are designed with strategic creases and slits that produce a particular shape when folded. When heated to 65 degrees Celsius, they fold. In the experiments, the exoskeletons lay flat on small heating pads. Once Primer moved on top of an exoskeleton, it affixed itself to it by hooking onto a water-dissolvable latch. When heat was applied, the exoskeleton folded up around Primer, taking the shape of a wing, a ball, a boat, or a shovel.
Other exoskeletons could take the form of a drill, a water scoop, a cutter, or grabber, the authors write. To shed the exoskeleton, Primer moves into water, which dissolves the latch and frees the robot. In the case of the boat, the latch doesn’t contact the water.
The work builds on previous research lead by Miyashita’s adviser, MIT roboticist Daniela Rus, showing that robots could assemble themselves into different shapes and even fold into specific shapes.
Miyashita said that Primer isn’t limited to wearing sheets of conductive plastic. Just like the hermit crab, Primer can don an object from its environment, such as a leaf, to use it as a tool or for camouflage.
Flexible in design and capability, Primer’s future could go in any number of directions.
“This could one day have applications in many different areas, from deep-sea construction to disaster-relief operations,” said Miyashita. “This work shows that it’s possible to design a robot that can keep rewriting its abilities.”
The team is now working to make the robot even smaller and more intelligent, and exploring different types of materials to make it more durable.