Researchers from ETH Zurich in Switzerland have developed a new type of microrobot that could transform stroke treatment. These tiny, magnetically guided robots swim through the bloodstream to deliver medication directly to blockages, offering a potentially safer alternative to current treatment methods.
Current stroke interventions typically involve injecting high doses of drugs to dissolve thrombus, or blood clots, in the blood vessels. This approach poses risks, including severe side effects such as internal bleeding. The innovative microrobots, however, are designed to navigate the complex circulatory system with precision, minimizing the amount of medication needed.
The microrobots consist of small, spherical capsules filled with lifesaving drugs and a radioactive tracer to aid in tracking their movement. According to the study published in the journal Science, these capsules are made from a soluble gel infused with iron oxide nanoparticles, enabling them to be magnetically guided.
Fabian Landers, a robotics researcher and coauthor of the study, explained, “Because the vessels in the human brain are so small, there is a limit to how big the capsule can be.” The team faced significant technical challenges in balancing size and magnetic properties to ensure effective navigation.
To enhance tracking, the researchers added tantalum nanoparticles, which allow for X-ray tracing. After years of development, they achieved a microrobot capable of maneuvering through the body’s approximately 360 arteries and veins. Bradley Nelson, another study coauthor, noted that magnetic fields are ideal for these minimally invasive procedures as they penetrate deeply into the body without causing harm.
Despite their small size, the efficacy of these delivery agents is crucial. To evaluate their invention, the team tested the microrobots using a catheter in artificial silicone models of both human and animal blood vessels. The catheter design included an internal guidewire connected to a polymer gripper that opens to release the microrobot.
Navigating the human arterial system is complex due to varying blood flow speeds. The guidance system employs three distinct strategies to maneuver through different arterial regions. The researchers successfully guided the microrobot at speeds of up to 4 millimeters per second using a rotating magnetic field. In some instances, the microrobot reached speeds of 20 centimeters per second, even moving against the blood flow.
Landers expressed amazement at the high speed of blood flow in human vessels, stating, “Our navigation system must be able to withstand all of that.” Following successful lab demonstrations, the team advanced to clinical trials using pigs. In 95 percent of test cases, the microrobot effectively delivered thrombus medication to the intended locations.
The researchers also tested the microrobot in a sheep’s cerebrospinal fluid, indicating its potential for a broader range of medical applications. Landers highlighted the significance of navigating such a complex anatomical environment, stating, “This complex anatomical environment has enormous potential for further therapeutic interventions.”
This groundbreaking research at ETH Zurich signals a promising advancement in stroke treatment, with the potential to improve patient outcomes and reduce risks associated with traditional methods. As microrobots continue to evolve, they may open new avenues in the field of medical technology.
