Researchers at Massachusetts Institute of Technology have created a printable origami robot. It only weighs a third of a gram, but it can swim, climb an incline, traverse rough terrain, and carry a load twice its weight. Furthermore, it folds itself to its designed shape from a flat sheet of plastic when heated and only measures about a centimetre from front to back.
This tiny robot is a very interesting machine as its only components are plastic sheet, from which it is made, and a permanent magnet affixed to its back. Such simple solutions are achieved because it is controlled by external magnetic fields. Cynthia R. Sung, one of the robot’s co-developers, said that “entire walking motion is embedded into the mechanics of the robot body”, while in previous attempts to create tiny origami robots “they had to design electronics and motors to actuate the body itself”.
The motivation to create such robot was its practical application in health sciences. It is thought that tiny sheets of material could be injected into the human body, navigate to an intervention site, fold themselves up, and, after the task is completed, completely dissolve. That is why scientists created this prototype from liquid-soluble materials that would dissolve in water or acetone.
One of the most important properties for such robot is its self-folding ability. In the prototypes such self-folding sheets had three layers, middle one always being polyvinyl chloride, a plastic commonly used in plumbing pipes. It shrinks when heated, providing folding up ability. Outer layers are different, depending in what kind of substance the robot needs to dissolve. There are slits cut into the outer layers by a laser cutter to guide the folding process. The researchers found that the sheet would begin folding at about 150 degrees Fahrenheit (about 65.5 degrees Celsius) and would fold to direction of the wider slits.
Robot is moved and controlled by external magnetic fields. The proper application of a magnetic field to the permanent magnet on robot’s back causes its body to flex. At first front feet remain on the surface, while the back feet lift. Then another sequence of magnetic fields causes front feet to move too and robot advances forward. During the tests, scientists positioned the robot on a rectangular stage with an electromagnet at each of its four corners and were able to control the magnetic field in such a way that robot moved at a pace of nearly four body lengths a second.
Scientists also made a prototype which is not liquid-soluble, but electrically conductive instead. It is meant to act as a sensor. It could contact with other objects, it would disrupt a current passing through the robot in a characteristic way, and that electrical signal could be relayed to human operators. This would be helpful in a variety of situations, as robot could contact chemical accretions in a mechanical system, microorganisms or cells in the body, or many other objects and substances.
The research is still not finished. Now scientists will continue to experiment with controlling of the robot and other potential materials it can be made of. They also want to see how much scaled down version they can make.