Miniature Robots to Navigate Blood Vessel Networks

Tiny, five-millimeter robots may be able to deliver drugs or redirect fluid flow within a 3D lumen network that closely mimics the structure of real blood vessels. 

Scientists at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany, have unveiled a groundbreaking technique for deploying these miniature robots. They’re designed with magnetic properties and take on a stent-like shape, which enables them to adapt to the changing geometry of the lumen (a hollow passageway through which blood flows). 

But effectively navigating through the network requires sufficient magnetic force to overcome friction and fluid flow. By dynamically adjusting the magnetic force—intensifying it for the active robot while reducing it for others—researchers ensured that individual robots could move as needed while others remained stationary. 

This technique, spearheaded by a research team at the Institute, holds the promise of revolutionizing minimally invasive therapies by enabling the simultaneous treatment of multiple hard-to-reach locations within the human body—an achievement beyond the reach of conventional medical tools. With the potential to significantly reduce procedure times and enhance therapeutic outcomes, this innovation could redefine how complex medical treatments are performed. 

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Soft miniature magnetic robots are unique in that they can navigate tiny spaces and are minimally invasive. Their use is potentially advantageous if not disruptive to current medical procedures and complex applications.

“This new method could one day enable the simultaneous treatment of multiple locations in hard-to-reach areas of the human body, which is currently unattainable with conventional tools. This innovative approach could significantly reduce procedure time and increase the effectiveness of minimally invasive therapies,” explained Chunxiang Wang, a doctoral student in the Physical Intelligence Department at Max Planck Institute. “Our soft miniature robots are shape-adaptable and are capable of minimally invasive accessing and navigating in enclosed, tortuous, and unstructured spaces that are clinically inaccessible or risky for tethered tools like catheters. At the targeted location, they can perform functions like delivering drugs or diverting the flow.” 

This technique could also add to the efficiency of therapeutic interventions and could even enable a prompter response to acute diseases such as thrombolysis for ischemic stroke at multiple locations with the use of numerous robots, Wang said.  

“In contrast, the dependence on a single robot navigating to the designated location, applying the medical functions, returning to the start location, and repeating the procedures for different locations would notably prolong the operation duration and miss the ideal treatment time window,” he continued. 

Biomedical functions are said to be spatiotemporal, or measured by data belonging to both space and time. By building efficiency of delicate complex biomedical functions in this realm, greater advances will be possible in biomedical procedures and applications. 

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“Deploying multiple of these magnetic soft robots can enhance the efficacy of biomedical functions spatiotemporally,” Wang added. “Multiple robots could concurrently execute therapeutic and diagnostic procedures at diverse locations. Examples include the interventional embolization of multiple cerebral tumors and aneurysms, as well as the distributed sensing of physiological properties facilitated by integrated electronic modules.”  

The team’s research specifically examines drug delivery over space and time for various diseases and treatments. By incorporating functional patches, it's possible to control both drug delivery and flow diversion, Wang said.  

“We are planning the in-vivo experiments to validate these functions inside animal bodies,” he continued. “The drugs can be embedded in the patch attached to the robot and will release when triggered. Certain stent cells are sealed to obstruct fluid flow into the lumen branch.” 

It is a challenge to control multiple magnetic robots simultaneously, since all the magnetic parts are affected by the magnetic field in some way. But the team’s work “provides a solution for multi-robot actuation, enhancing applications across various miniature soft robotic device designs—like commercial medical capsules—in complex environments,” Wang said.

Jim Romeo is a technology writer in Chesapeake, Va.