Credit: Renee Zhao, Mechanical Engineering, Stanford University
A robot as small as a pea can roll, turn and jump. It can move effortlessly from a dry to a liquid surface, just like a frog or salamander. Other small robots do not imitate him: they can only move in one direction.
With its small size and unprecedented maneuverability, this new robot could move inside a patient’s body to deliver a highly targeted medical dose.
The robot can avoid obstacles because it is built according to the ‘Kresling pattern’. That is, the design consists of a stack of right-angled triangles, which makes it look like a crushed cylinder with ribs. This model enables the robot to move through liquids.
‘Our goal was to combine the geometric properties and the foldability of origami in the robot. With that, we hoped to make navigation more efficient and enable the robot to deliver medicine,” said Renee Zhao, an assistant professor of mechanical engineering at Stanford University.
There is a small hole in the robot through which you can place a small load in the machine’s belly. The operator can control the device wirelessly with a magnet. The magnetic fields used for this are comparable to those found in MRI machines. “The aim is to connect the robot with the MR system. That way, we can control it while the patient is being scanned by the imager,” says Zhao.
Some versions of the robot have two magnets sitting on either side of the cylinder. The operator can generate rotational force between these magnets. This ensures that the plastic body is compressed. If the operator does this several times in succession, the robot acts as a kind of pump that disperses liquid.
When the robot needs to move through a liquid while swimming, the operator makes it rotate. It does this through a rotating magnetic field. Thanks to the suction power of the rotating movements, the load remains in the stomach. Only when the robot has arrived at the right place does the operator stop turning and deliver the dose.
In principle, the mini-robot can administer both liquid and solid medicine, for example in the digestive tract. Only soft materials have been used to build the machine so that the tissues cannot be damaged. Even the magnet is flexible. The rest of the body is made up of tiny glass beads, metal nanoparticles and flexible plastic.
The researchers performed a test by moving the robot in an empty and a full pig stomach. The final destination was determined by the operator, but the machine itself knew how to get to its final destination. When there was a large obstacle in the way, the operator could make the robot jump short by strengthening the magnetic field. With a large pile of liquid, he could start swimming without any problems.
It is impressive that such a simple model can guarantee so much versatility. “It’s interesting to see how the researchers were able to incorporate all these features into one integrated design,” said Siyu Xu, a postdoctoral robotics engineer at the Harvard Microbotics Lab who was not involved in the study. According to Xu, most robots specialize in only one movement: walking, crawling, swimming or flying.
The new origami design can provide inspiration for new mini-robots, says Zhao. “The robots can help with different kinds of diseases and applications,” she says. She and her colleagues are now working to reduce the size of the machines to fit into the circuit. But they will also make slightly larger versions that can perform smaller operations with cameras and forceps. Zhao wants to give the robots even more skills, but they keep the same simple design.
Translation: Gwen Pauwels