Fascination with technology Magnetic Robot Changes Its Shape in Real Time

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Max-Planck-Institut für Intelligente Systeme

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In our "Fascination with Technology" section, we present impressive research and development projects to designers every week. Today: how a Matryoshka-like soft robot achieves unprecedented shape-shifting capabilities.

In a recent study, scientists at the Max Planck Institute for Intelligent Systems in Stuttgart presented a method that allows them to reprogram a stack of small, flexible, and magnetic tubes in real-time and on-site. By rearranging and recombining the magnetic units of each tube, the Matryoshka-like robot achieves unprecedented shape-shifting capabilities, opening up new possibilities for soft robotics. Such soft robots could be used for a variety of applications, including in medicine.

Until now, the magnetization profiles of magnetic robots were typically fixed. When exposed to an external magnetic field, they were difficult to alter in real-time and on-site. Researchers at the Max Planck Institute for Intelligent Systems (MPI-IS) have introduced a new method in a research paper that allows them to realign the magnetization of the small robots. This enables the scientists to quickly adapt the shape to specific conditions, significantly increasing the complexity of such robots.

• Under the leadership of Prof. Dr. Metin Sitti, former director of the Physical Intelligence Department at MPI-IS and now president of Koç University in Istanbul, the team stacked several tubes inside each other like Matryoshka dolls.
• As shown in figure 1A, tube C is embedded in tube B, which in turn is embedded in tube A.
• Each contains one or more magnetic units, and the magnetization profile of each magnetic unit can be preprogrammed as needed (Figure 1B).
• When the way the tubes are stacked is changed—they are pulled apart or moved closer together—the relative position of the magnetic units changes, and with it the entire magnetization profile of the entire tube stack (Figure 1C).

Shape Change in Real Time

Such real-time shaping and transformation on-site was not possible with previous magnetic soft robots. Now, however, under a constant magnetic field, a previously straight tube can, for example, be deformed into a helix (Figure 1D) or in the opposite direction (Figure 1E). Furthermore, this approach can be extended to two- and three-dimensional constructions, allowing a transition from one shape to another in real-time without changing the magnetic field (Figures 1F and 1G).

Since the focus at Max Planck Institutes is primarily on curiosity-driven basic research, the team also investigated how this method could be applied in various scenarios, such as navigating around objects without contact, reprogramming cilia- or flagella-like micro-robots, or coordinating the collaboration of multiple instruments under the same magnetic field.

Use in Medicine Conceivable

The researchers' work could one day also find practical applications, for example in medicine—particularly in minimally invasive, image-guided treatment of vascular diseases. In this procedure, doctors guide a catheter and a guidewire through blood vessels to the target site to make a diagnosis or administer therapy. As the catheter navigates through curved vessels, friction and contact with the vessel wall are unavoidable. This can cause damage, delay recovery, and, in severe cases, lead to medical complications. Older patients, in particular, often opt against such procedures and prefer medication instead.

The new technology offers an alternative: by adjusting the catheter's magnetization profile in real-time to match the path ahead, friction and contact could be significantly reduced or even entirely avoided. This would minimize damage to delicate tissue, promote faster recovery, and make vascular procedures a viable option for people who, due to their age or the fragility of their vessels, would otherwise avoid these treatments.

Our original goal was to develop a method to instantly and in situ change a magnetization profile. During the research, we discovered unexpected capabilities such as shape retention and magnetic neutralization, which open up new possibilities for technologies like catheter design and the reprogramming of cilia arrays.

Xianqiang Bao, First author of the publication

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