The 1990s nanotechnology dream of tiny robots swimming through our blood stream to treat disease is moving (verrrry) slowly but surely toward reality. In a new milestone, researchers used an external magnetic field to steer microbots through a live mouse's body carrying therapeutic stem cells. From IEEE Spectrum:
..Delivering stem cells typically requires an injection with a needle, which lowers the survival rate of the stem cells, and limits their reach in the body. Microrobots, however, have the potential to deliver stem cells to precise, hard-to-reach areas, with less damage to surrounding tissue, and better survival rates, says Jin-young Kim, a principle investigator at DGIST-ETH Microrobotics Research Center, and an author on the paper....
The team fabricated the robots with 3D laser lithography, and designed them in two shapes: spherical and helical. Using a rotating magnetic field, the scientists navigated the spherical-shaped bots with a rolling motion, and the helical bots with a corkscrew motion. These styles of locomotion proved more efficient than that from a simple pulling force, and were more suitable for use in biological fluids, the scientists reported....
Kim says he and his colleagues are developing imaging systems that will enable them to view in real time the locomotion of their microrobots in live animals.
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The 3D-printed robot above weighs just one milligram and is only 2.5mm at its longest point. Designed by University of Maryland mechanical engineer Ryan St. Pierre and his colleagues, it is likely the smallest walking robot in the world. Video of the microbot scurrying along is below. From IEEE Spectrum:
Like its predecessors, this robot is far too small for traditional motors or electronics. Its legs are controlled by external magnetic fields acting on tiny cubic magnets embedded in the robot’s hips. Rotating magnetic fields cause the magnets to rotate, driving the legs at speeds of up to 150 Hz. With all of the magnets installed into the hips in the same orientation, you get a pronking gait, but other gaits are possible by shifting the magnets around a bit. Top speed is an impressive 37.3 mm/s, or 14.9 body lengths per second, and somewhat surprisingly, the robot seems to be quite durable—it was tested for 1,000,000 actuation cycles “with no signs of visible wear or decreased performance.”
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Continuing the quest to design robots that could travel through our bodies to deliver drugs and cure disease, researchers at EPFL and ETH Zurich demonstrated tiny shape-shifting microrobots that swim through blood vessels. Made from hydrogel nanocomposites, the microbots can fold into various shapes for easy travel through tight spaces and flowing with dense, viscous, or fast-moving liquids. The microbots are peppered with magnetic nanoparticles so that they can be "steered" with an external magnetic field. From EPFL:
“Our robots have a special composition and structure that allow them to adapt to the characteristics of the fluid they are moving through. For instance, if they encounter a change in viscosity or osmotic concentration, they modify their shape to maintain their speed and maneuverability without losing control of the direction of motion,” says (EPFL researcher Selman) Sakar.
These deformations can be “programmed” in advance so as to maximize performance without the use of cumbersome sensors or actuators. The robots can be either controlled using an electromagnetic field or left to navigate on their own through cavities by utilizing fluid flow. Either way, they will automatically morph into the most efficient shape.
"Smart microrobots that can adapt to their surroundings" (EPFL)
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