Researchers at ETH Zurich in Switzerland have developed innovative microrobots that could revolutionize stroke treatment. These tiny, magnetically guided beads are designed to navigate the complex human circulatory system to deliver lifesaving medication directly to blockages in blood vessels. This breakthrough, detailed in a recent study published in the journal Science, aims to reduce the risks associated with current treatment methods.
Current stroke interventions typically involve injectable drugs that dissolve thrombi—dangerous clots that obstruct blood flow. However, this approach often requires high dosages due to the vastness of the circulatory system, which can lead to serious side effects such as internal bleeding. The team at ETH Zurich believes their new method offers a safer alternative.
The microrobots are encapsulated in a soluble gel that contains iron oxide nanoparticles, allowing for magnetic guidance. According to Fabian Landers, a robotics researcher and co-author of the study, the challenge was to create a capsule small enough to navigate the brain’s narrow blood vessels while maintaining sufficient magnetic properties.
To enhance tracking capabilities, the researchers incorporated tantalum nanoparticles, which facilitate X-ray tracing of the microrobots’ movements. After years of research, the team successfully developed a magnetic microrobot capable of navigating the body’s approximately 360 arteries and veins.
Bradley Nelson, another co-author and microrobotist, explained the advantages of using magnetic fields for this type of minimally invasive procedure. He noted that these fields penetrate deep into the body without causing harm at the levels they employ.
Testing the efficacy of their invention, the researchers first used a catheter to inject the microrobot into artificial silicone models simulating human and animal blood vessels. The catheter, featuring an internal guidewire linked to a polymer gripper, releases the microrobot, enabling it to navigate through the complex vascular landscape.
The variability of blood flow speeds across the arterial system presents significant challenges. To address this, the guidance system employs three distinct strategies. In one approach, a rotating magnetic field allows precise control of the microrobot at speeds of up to 4 millimeters per second. In other scenarios, a shifting magnetic gradient propels the device against blood flow, achieving speeds of up to 20 centimeters per second.
Landers highlighted the remarkable nature of blood flow within the human body, emphasizing the need for a robust navigation system. “Our navigation system must be able to withstand all of that,” he stated.
Following successful laboratory demonstrations, the team proceeded to clinical trials using pigs. The results were promising, with the microrobot delivering thrombus medication to the correct location in 95 percent of test cases. Additionally, initial tests in a sheep’s cerebrospinal fluid suggest that these microrobots could have broader applications in various medical fields.
“This complex anatomical environment has enormous potential for further therapeutic interventions,” Landers remarked, expressing enthusiasm for the microrobot’s ability to navigate challenging conditions.
As research continues, these microrobots could pave the way for more effective and safer treatments for strokes and potentially other medical conditions, marking a significant advancement in the field of medical robotics.
