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Headline: RAW VIDEO: Tiny robot to go on 'Fantastic Voyage' to deliver drugs inside our bodies
Caption: Swiss scientists have developed a tiny robot capable of transporting drugs to precise locations within the body - a breakthrough they say could soon be used in hospitals. The research from ETH Zurich, which has echoes of scenes from the 1966 sci-fi film Fantastic Voyage in which a tiny submarine-style ship travels around the human body, has been published in Science. With no shrink ray to miniaturise a crew, these tiny robots are unmanned but are steered by magnets. The microrobot consists of a spherical capsule made from a soluble gel shell. The capsule contains iron oxide nanoparticles, giving it magnetic properties and allowing doctors to steer it through the body. Around 12 million people worldwide suffer a stroke each year. Many die or are left with permanent disabilities. At present, clinicians administer drugs that dissolve the blood clot blocking the vessel. But because these medicines circulate throughout the body, high doses are required to ensure enough of the drug reaches the clot - increasing the risk of serious side-effects such as internal bleeding. Researchers have long sought ways to use microrobots to deliver medicines directly to where they are needed. “Because the vessels in the human brain are so small, there is a limit to how big the capsule can be. The technical challenge is to ensure that a capsule this small also has sufficient magnetic properties,” says Fabian Landers, lead author and postdoctoral researcher at ETH’s Multi-Scale Robotics Lab. The microrobot also needs to be visible on X-ray scans. For this, the team turned to tantalum nanoparticles — common in medicine but difficult to work with because of their density. ETH Professor Bradley Nelson, a veteran of microrobotics research, said: “Combining magnetic functionality, imaging visibility and precise control in a single microrobot required perfect synergy between materials science and robotics engineering, which has taken us many years to successfully achieve.” Chemist Professor Salvador Pané and his team developed the precision iron oxide nanoparticles needed to strike this balance. The robots can be loaded with a range of medicines — in this study, a clot-dissolving drug, an antibiotic or a cancer treatment. A high-frequency magnetic field heats the nanoparticles, dissolving the gel shell and releasing the drug. Doctors deploy the microrobot using a catheter equipped with a flexible polymer gripper. Once in position, the gripper opens and releases the capsule. The team used a two-step approach: first injecting the capsule into the bloodstream or cerebrospinal fluid, then steering it to its target using an electromagnetic navigation system. To navigate the body’s complex network of vessels, researchers built a modular electromagnetic system designed for operating theatres. “The speed of blood flow in the human arterial system varies a lot depending on location. This makes navigating a microrobot very complex,” Nelson says. Three navigation strategies were developed. One uses a rotating magnetic field to roll the capsule along vessel walls at speeds of 4mm per second. Another employs a magnetic field gradient strong enough to pull the capsule even against blood flowing at more than 20cm per second. “It’s remarkable how much blood flows through our vessels and at such high speed. Our navigation system must be able to withstand all of that,” says Landers. A third method, known as in-flow navigation, directs the magnetic gradient so that the capsule is carried into the correct branch of a vessel at junctions. Across the test scenarios, the microrobot delivered its drug to the correct location in more than 95% of cases. “Magnetic fields and gradients are ideal for minimally invasive procedures because they penetrate deep into the body and — at least at the strengths and frequencies we use — have no detrimental effect on the body,” Nelson adds. To trial the system safely, the team created silicone models replicating human and animal vessels. These models are now used in medical training and sold commercially by ETH spin-off Swiss Vascular. “The models are crucial for us, as we practised extensively to optimise the strategy and its components. You can’t do that with animals,” Pané says. In these models, the microrobot was able to locate and dissolve a blood clot. Subsequent animal tests showed the navigation methods worked in pigs and that the robot remained visible throughout the procedure. The team also steered microrobots through the cerebrospinal fluid of a sheep. Landers explains: “This complex anatomical environment has enormous potential for further therapeutic interventions, which is why we were so excited that the microrobot was able to find its way in this environment too.” Beyond stroke treatment, the microrobots could be used for localised infections or tumours. The researchers say their ultimate aim is to ensure the technology is ready for clinical use as soon as possible, with human trials the next step. “Doctors are already doing an incredible job in hospitals. What drives us is the knowledge that we have a technology that enables us to help patients faster and more effectively and to give them new hope through innovative therapies,” Landers concludes.
Keywords: feature,photo,video,fantastic voyage,robot,science,medicine
PersonInImage: Micro robot completely dissolves thrombus.