Medical innovation – micro-robots in our bloodstream will soon fight cancer – Knowledge


Use medicines only exactly where they are needed in the body – this should be possible thanks to the smaller robots whizzing through our bloodstream.

A submarine and its crew are so small that they can circle a patient’s arteries and veins and remove a dangerous blood clot there. What was still intended as science fiction in the 1966 film “The Fantastic Voyage” is now getting quite close to reality.

One-tenth of a hair tall

Today, numerous universities are working on micro-robots. For example, they should deposit medicinal substances right next to the brain in cancerous tumors. Robots are not visible to the naked eye. They measure a tenth of the width of a hair. Simone Schürle works with these microbots at ETH Zurich.

They don’t have to be too big, or they risk obstructing blood flow. Not too small either, because otherwise they would be quickly excreted by the kidneys.

Walking in swarms

Schürle sends out entire swarms of these micro-robots to be able to carry enough medicinal substances. The robots look like balls, but they don’t have mopeds. They are swept through the bloodstream with the bloodstream.

So far, this has only been done experimentally or in animal experiments. The microrobots are then activated in the right place by ultrasound or magnetic fields: “This is how we turn robots out of the vessel wall and into tumors,” says Schürle.

Hitherto invisible from the outside

The problem is, because microrobots are so small, they can’t be tracked in real time from outside the body. Measurements show that most micro-robots have not yet achieved their goal. They are broken down by the body. “At worst, however, they could have a toxic effect in the wrong place,” says Daniel Razansky, also from ETH Zurich. He is a professor of biomedical imaging.

Together with Metin Sitti, one of the world’s leading micro-robotics engineers at the Max Planck Institute for Intelligent Systems in Stuttgart, Razansky has now found a way to be able to follow micro-robots from the outside, i.e. on the screen.

Visible thanks to the gold layer

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To make the microrobots visible from outside the body as well, the researchers further developed the capsules. “We coated half of the spherical microrobots with gold,” says Daniel Razansky of ETH Zurich, “the other half with nickel.” Gold acts as a contrast medium for so-called optoacoustic imaging, a special tomography technique that researchers have developed so that microrobots can also be seen from the outside deep into the body, with high resolution and in real time. The researchers used nickel so that the microrobots could be maneuvered from outside the body. With a magnet, the nickel-plated spheres are drawn through the bloodstream, as it were, even against the bloodstream.

They tested the new imaging method on sleeping lab mice. The microrobots, which wandered through the bloodstream in the brains of the mice, were clearly visible from the outside.

A look inside a mouse's brain with five microrobots circulating in its bloodstream (green dots).


A look inside a mouse’s brain with five microrobots circulating in its bloodstream (green dots).

ETH Zurich

Companies want to turn microrobots into cash

So far, microrobotics have been blind, so to speak, Razansky says. Thanks to the latest development, which has just been released, it is only now becoming visible what is really going on in the body with microrobots. This is an important step, Schürle also confirms.

There are already several start-ups around the world that want to bring micro-robots to market. However, it is still not that far away that microrobots can be used in humans. According to Schürle and Razansky, it will take a few years or even decades, depending on the application.

On a tear to freedom

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However, the possibilities of using medical microbots in our bodies are very diverse. One day they might even be moving in the eye, for example to heal the retina at the back of the eyeball. Here, too, technological progress has almost reached science fiction. In the 1966 film “The Fantastic Voyage”, the mini-doctors in the mini-submarine managed to escape after an attack of antibodies in the optic nerve of one eye. From there they then swim to freedom on a tear.

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