In the science fiction classic "The Fantastic Journey", American scientists shrink a submarine and its crew to the size of a micrometer in order to carry out repair work - in the brain of their colleague.

It's a kind of space adventure, just in the depths of the body.

Metin Sitti, Director at the Max Planck Institute for Intelligent Systems in Stuttgart, did not invent any shrink rays, but instead his team is developing small medical robots that are to be used, for example, in the digestive tract and in the bloodstream of a person.

Who would voluntarily put robots in their bodies?

Well, first of all, patients who have no other choice, says Sitti.

Blackmail?

No, rescue: about half of the aneurysms in the brain cannot be reached with endoscopic instruments.

If the bulge in the artery expands, there is a risk of cerebral hemorrhage.

Wireless mini machines could swim or crawl to the affected area.

Other ideas: The robots could bring drugs to where they are needed, they could also make diagnoses and, why not, one day do surgery from the inside.

"My dream is to be able to do this in five to ten years"

In contrast to the mini submarine from the film “The Fantastic Journey”, Sitti's robots are not attached to rigid cylinders with tools. They are malleable, compact and soft. One looks like a jellyfish, another like a strip of chewing gum that flops forward like a crumple and hurls itself over larger obstacles with one jump. Just because the robots look harmless to the human eye doesn't mean that the immune system would see it the same way.

This problem already arises in the film "The Fantastic Journey": The arterial divers have to fight not only a Soviet double agent but also with white blood cells. You have to try a lot, says Metin Sitti, until you have the right size, the right material and the right shape so that you don't challenge the immune system. The robots are moved with the help of an externally applied rotating magnetic field. This supplies the machines with energy, because they have no storage of their own, and guides them along their path. Sitti demonstrates this in his lecture with a cordless screwdriver with a cube-shaped object, a magnet, attached to its head.

The microrobots are no longer science fiction, but clinical application is not just around the corner either.

So far, courses have mainly been mastered in the laboratory.

How much longer does it take for use on aneurysm patients?

“My dream is to be able to do this in five to ten years,” says Sitti.

Before doing this, you have to rule out risks, including with tests on animals.

If a magnet fails, the robots shouldn't be lost somewhere in the patient, and they shouldn't clog a cerebral artery.

And how do you get these things out in the end?

That depends on the application.

At best, says the engineer, they would be broken down by the body itself after use.