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ETH Zurich's artificial bacterial flagella can measure just over 20 micrometers long, less than half the width of a human hair.  (Source: Institute of Robotics and Intelligent Systems/ETH Zurich)
Man-made bacteria may be useful in fighting man-borne illnesses like cancer and atherosclerosis.

Much research has gone into the medical field of microscopic man-made devices. Carbon nanotube devices have seen quite a bit of excitement as well as other interesting designs. Researchers at ETH Zurich in Switzerland have created another modern marvel to use in the war against the ills that plague mankind.

The design, which is based on harmful bacteria like E. coli, is called an Artificial Bacterial Flagella or ABF. Like little corkscrews, the microscopic manufactured flagella can be manipulated to move through the body by magnetic fields. Theoretically, the ribbons could be used as delivery systems or for cleaning plaque from arteries.

The manufacturing process that ETH Zurich used to create the flagella is known as vapor deposition. Ultra-thin layers of separate elements, in this case indium, gallium, arsenic and chromium, are deposited onto a substrate. When a ribbon is cut from the composed film, it naturally creates a spiral which size and shape are dependent on the thickness of each layer of the film. By varying individual layers, the researchers can control how tight the spiral is and even which way the spiral winds.

To control the movement of the flagella, a small piece of film, also created by vapor-deposition, is attached to one end of the corkscrew. This head is composed of chromium, nickel and gold, only one of which, the nickel, has any reaction to magnetic fields. With the head attached, the team can drive the flagella around by varying the magnetic field around it. The device can move and rotate in any direction, thanks to custom software designed specifically for the system.

Though the current samples measure between 25 and 60 micrometers and can move at a speed of about 20 micrometers per second, the team is working to further shrink the size and boost the speed capabilities of the system. More work will need to done before the devices can be put to use, in fact, as tracking and control system of even higher precision would be necessary for safe use in humans.





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