MIT researchers have developed a printable origami-inspired robot that, when heated, folds itself up from a flat sheet of plastic. The robot weighs a third of a gram and measures about a centimeter from front to back.

The folding bot can climb an incline, traverse rough terrain, and carry a load twice its weight. A permanent magnet is affixed to its back.

Once the robot has folded itself, the proper application of a magnetic field causes the body to flex. The friction between the robot’s front feet and the ground keep the front feet steady while the back feet lift. Another sequence of magnetic fields enables the robot’s body to twist slightly, which breaks the front feet’s adhesion and moves the body forward.

In their experiments, the researchers positioned the robot on a rectangular stage with an electromagnet at each of its four corners. They were able to vary the strength of the electromagnets’ fields rapidly enough that the robot could move nearly four body lengths a second.

In addition to the liquid-soluble versions of their robot, the researchers also built a prototype whose outer layers were electrically conductive. The researchers envision that a tiny, conductive robot could act as a sensor. Contact with other objects — whether chemical accretions in a mechanical system or microorganisms or cells in the body — would disrupt a current passing through the robot in a characteristic way, and that electrical signal could be relayed to human operators.