Nov 19, 2025
3 min read
Magnet-guided Microrobot destroys the blood system.
Tiny robots could be an effective tool in breaking down dangerous bulges in blood vessels that cause the brain.But robots focus on technical methods rather than machine maintenance.Instead, they are small beads that perfectly hold the rescue medication and contain a small amount of radioactive Tektronix that helps doctors track their journey.
Current treatments for stroke patients often involve injectable medications that dissolve a blockage in the blood vessel called a thrombus.Given the extent of the circulatory system, the procedure often requires a high dose of medication to ensure that an adequate amount reaches the target area.This makes the procedure itself risky, with possible serious side effects, including internal bleeding.
Robotics researchers at ETH Zurich in Switzerland now believe that an alternative strategy may be on the way.In a study published in the journal Science, they designed a soluble gel capsule with iron oxide nanoparticles strong enough to be magnetic.
"Because the vessels in the human brain are so small, how big can a capsule be?The technical challenge is that the capsule is small and has sufficient magnetic properties," said Fabian Lands, a robotics researcher and study associate.
Landers and his team added nanoparticles of the element tantalum to allow X-ray tracking.It took years to find the right balance of components, but the researchers say they now have a magnetic microrobot capable of reliably navigating the roughly 360 arteries and veins in the human body.
"Magnetic fields and gradients are ideal for minimally invasive procedures. Because they penetrate deep into the body. And at least in the strength and frequency we use it. There are no harmful effects on the body," explains the co-author and co-author of the Microrobots study Bradley Nelson.
However, these tiny delivery agents are only as good as their effectiveness.To test their invention, Landers and Nelson first used a catheter to inject the tiny robot into artificial silicone models of human and animal blood vessels.Building on an already available design, the specialized catheter includes an internal guidewire attached to a polymer handle that opens to release the tiny robot.However, it is not as easy as controlling the device slowly and at one speed until it reaches its destination.
"The speed of blood flow in the human arterial system varies greatly depending on location. This makes navigating a microrobot very difficult," Nelson said.
This means that the guidance system relies on three independent strategies to navigate each position of the head. Using the rotating magnetic force, the team effectively and precisely guides the microrobot at a speed of up to 4 meters per second.
In another model, a variable magnetic field gradient pulls the device into a strong field, even against the current of blood flow.In some cases, the microrobot reaches a speed of 20 centimeters per second.
"It's amazing how much blood flows through our blood vessels at such high speeds," says Landers. "Our navigation systems have to be able to handle all of that."
After successful lab tests, researchers moved to clinical trials using pigs.In 95 percent of the test cases, the microrobot delivered the antithrombotic drug to the right place.This method also shows promise with sheep cerebrospinal fluid, indicating that it can be used in many other medical applications.
"This complex anatomical environment has tremendous potential for other therapeutic interventions, so we were so excited that the microrobot could find its way into this environment as well," said Landers.
