Nanotechnology Magnetically Controlled Microrobot Moves Through Blood Vessels

A soft microrobot swims through narrow vessels, following magnetic fields. Researchers aim to precisely deliver active substances and reach hard-to-access regions. The experiments are still ongoing in the laboratory.

A team from ETH Zurich has introduced a microrobot that moves through narrow blood vessels using targeted magnetic fields. The millimeter-sized body made of a soft polymer responds to changes in the magnetic field, allowing it to even swim against the simulated blood flow.

The researchers rely on a gel capsule containing iron oxide nanoparticles for magnetic control and tantalum nanoparticles for X-ray visibility. The material deforms as soon as external coil systems apply a new magnetic field. This allows the capsule to roll along the vessel wall, be pulled through the vessel via field gradients, and be precisely directed at branches. The goal is to place active substances more accurately than would be possible with catheters or syringes.

Control Via Coils And Imaging

To control the movement, the researchers use a modular electromagnetic navigation system with multiple coils. These generate directed magnetic fields that propel the microrobot. X-ray imaging captures its position in real-time. The researchers combine various navigation strategies to guide the path through complex vascular structures.

The technical effort is high: the coils require precise control to ensure the robot does not get stuck or trapped in swirling currents. At the same time, the magnetic fields must remain weak enough to avoid affecting the surrounding tissue. This succeeds in the laboratory, but for medical applications, significantly more robust and compact systems are needed.

Laboratory Tests, But No Application Yet

It will take time before the microrobot operates in actual blood vessels. Current experiments are being conducted in vascular models as well as in animal trials with pigs and a sheep. The microrobot functions without its own electronics; navigation and release are controlled exclusively by external magnetic fields and imaging. The researchers use medically established nanoparticles, such as iron oxide and tantalum, yet the entire capsule requires regulatory approval. Nevertheless, the research demonstrates that magnetically controlled microsystems are moving with increasing precision and could one day perform tasks that currently require invasive procedures.

Strictly speaking, the bead is not a robot in the true sense—at most in the broadest sense: the structure contains no electronics, no sensors, and no autonomous control. The capsule responds solely to external magnetic fields, altering its shape and movement as a result. Technically, it is therefore a passive microsystem guided externally. Nevertheless, the term "robot" has become common, as the capsule can be precisely maneuvered and perform tasks such as transport and positioning. (mc)

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