Magnetic robot that walks, crawls and swims – Robohub

MIT professor of materials science and engineering and brain and cognitive science Polina Anikeeva in her lab. Photo: Steph Stevens

By Jennifer Michalowski | McGovern Institute for Brain Research

MIT scientists have developed tiny, soft-bodied robots that can be controlled by a weak magnet. The robots, made up of rubber magnetic spirals, can be programmed to walk, crawl, swim — all responding to a simple, easy-to-apply magnetic field.

“This is the first time that this has been done to be able to control the three-dimensional motion of the robot using a one-dimensional magnetic field,” said Professor Polina Anikeeva, whose team published an open access paper on the robot. -magnetic boots, said. magazine Advanced Materials. «And because they’re mostly polymers and soft polymers, you don’t need a huge magnetic field to activate them. Anikeeva, professor of materials science and engineering and brain and cognitive sciences at MIT, co-investigator at the McGovern Institute for Brain Research and associate director of MIT, adds: It’s actually a very small magnetic field that drives these robots. Electronics Research Laboratory and director of MIT’s K. Lisa Yang Body-Brain Center.

The new robots are well-suited to transporting goods through confined spaces and their rubber bodies are gentle in fragile environments, opening up the possibility that this technology could be developed for biomedical applications. Anikeeva and her team have built their robots to millimeters long, but she says the same method can be used to make much smaller robots.

Magnetic actuated fiber-based soft robot

Magnetic robot engineering

Anikeeva says that so far, the magnetic robots have moved in response to moving magnetic fields. For these models, she explains, “if you want your robot to walk, your magnet will go with it. If you want it to rotate, you rotate your magnet.” That limits the settings in which such robots can be deployed. “If you are trying to operate in a really confined environment, moving magnets may not be the safest solution. She explains that you want a stationary device that only applies the magnetic field to the entire sample.

Dr. Youngbin Lee ’22, a former graduate student in Anikeeva’s lab, has come up with a solution to this problem. The robots he developed in Anikeeva’s lab are not uniformly magnetized. Instead, they are strategically magnetized in different regions and directions so that a single magnetic field can trigger the motion-controlled configuration of the magnetic forces.

Before they can be magnetized, however, the robot’s flexible, lightweight body must be built. Lee started the process with two types of rubber, each with a different hardness. They are clamped together, then heated and stretched into a long, thin thread. Due to the different properties of the two materials, one of the rubbers retains its elasticity through this stretching process, but the other deforms and cannot return to its original size. So when the tension is released, one layer of the yarn contracts, pulling the other side and pulling the whole thing into a tight coil. Anikeeva said the spiral fibers are modeled on the spirals of cucumber plants, spiraling when one layer of cells loses water and shrinks faster than the second.

A third material – a material with particles capable of becoming magnetic – is incorporated in a channel that runs through the rubber thread. So, once the spiral has been created, a magnetization model that allows a specific type of motion can be included.

“Youngbin thought very carefully about how to magnetize our robots to make them move the same way he programmed them to move,” says Anikeeva. «He calculated to determine how to set up such a force on it when we applied a magnetic field that it would actually start walking or crawling.»

For example, to form a robot that crawls like a caterpillar, the spiral is shaped into gentle ripples, then the body, head and tail are magnetized so that the magnetic field is applied perpendicular to the plane of transfer. The robot’s movements will cause the body to compress. When the field drops to zero, the compression is released and the crawling robot elongates. Together, these movements propel the robot forward. Another robot in which two foot-like spirals are connected to a patterned magnetized joint that allows for a more walking-like movement.

biomedical potential

This precise magnetization creates a program for each robot and ensures that once the robots are created, they are easy to control. The weak magnetic field activates the program of each robot and controls the specific movement pattern of the robot. A single magnetic field can even cause multiple robots to move in opposite directions, if they have been programmed to do so. The team found that a small manipulation of the magnetic field has a beneficial effect: By flipping a switch to reverse the magnetic field, a cargo robot can shake it gently and release its payload.

Anikeeva says she can envision these soft-bodied robots — simple to manufacture that would easily scale up — transporting materials through narrow pipes, or even inside the human body. For example, they can deliver a drug through narrow blood vessels, releasing the drug exactly where it’s needed. She says that magnetically activated devices also have biomedical potential beyond robotics and could one day be integrated into artificial muscles or tissue-regeneration aids.

MIT News

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