Slime driven by a magnetic field can squeeze through tight spaces and grab objects. That makes it ideal for applications within the body.
The magnetic slime robot has a yogurt-like consistency. He can crawl through narrow corridors and grab objects. Within the body, the slime robot can perform all kinds of tasks, such as finding swallowed objects.
Elastic robots and fluid-based robots that can move in small spaces already exist. But robots that have both properties are rarer.
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Detergent and resin
Li Zhang, a professor of engineering at the Chinese University of Hong Kong, and colleagues mixed neodymium magnetic particles with borax (a commonly used detergent) and polyvinyl alcohol (a type of resin). This created a slime that can be controlled by an external magnetic field. They then added a layer of silicon over the magnetic particles so that they do not cause toxic effects in the human body.
Consecutive tasks
The team tested the robot in different scenarios. For example, they had the robot grasp a ‘swallowed’ battery in a fake stomach, grasp a wire and squeeze itself through holes of a millimeter in size.
The slime seems to be able to perform several tasks sequentially with ease. It also repairs itself when cut into pieces. ‘You can first let it stretch so long that it resembles a flow of liquid. Then you can roll it up like an octopus arm to carry something,” says Zhang.
Before it can be used in humans, we must first have a way to track the mucus within the body, says Pietro Valdastric† He is professor of robotics at the University of Leeds. ‘If you want to direct something within the body to perform a certain task, you have to know where the [robot] is and how he does it.’
Safety
Extensive testing must also be carried out to ensure that the toxic magnetic particles cannot escape from the mucus. “They should be able to guarantee safety with future trials, but it’s definitely a good approach,” Valdastri says.
Right now, the slime can only move slowly, at a speed “similar to that of an insect,” Zhang says. But he says tinkering with the magnetic field could improve speed in the future. Follow-up research could also make the mucus work on its own, he says.