Microscopic Robots Could Swim Inside Human Arteries

Miniature Robots with micro-motors small enough to be injected into the human bloodstream could assist in a range of complex surgical operations necessary to treat stroke victims, confront hardened arteries, or address blockages in the bloodstream.

Researchers at Monash University (Melbourne, Australia) are developing remote controlled miniature robots small enough to swim into blood vessels catheters were unable to reach previously, such as those in the labyrinthine structure of the brain. These "microbots” are becoming a reality thanks to a piezoelectric motor that is just 250 μm--a quarter of a millimeter--wide, which has been dubbed the Proteus motor. The researchers decided to focus on piezoelectricity as the most suitable energy force for micro-motors, since it can be scaled down significantly while still remaining forceful enough to swim against the flow of blood, reaching spots difficult to operate upon. With the right sensor equipment attached to the microbot, the view of (for example) a patient's troubled artery can be improved, and the surgeon's dexterity could be enhanced by his ability to work remotely. The research team has so far produced prototypes of the motor, and is now working on ways to improve the assembly method and the mechanical flagella, which propels the micro robots. The development of the Proteus motor was described in the January 2009 issue of the Journal of Micromechanics and Microengineering.

"Opportunities for micro-motors abound in fields as diverse as biomedicine, electronics, aeronautics, and the automotive industry. Responses to this need have been just as diverse, with designs developed using electromagnetic, electrostatic, thermal, and osmotic driving forces,” said leader of the research team Professor James Friend, Ph.D., of the Micro/Nanophysics Research Laboratory at Monash. "Piezoelectric designs, however, have favorable scaling characteristics and, in general, are simple designs, which have provided an excellent platform for the development of micro-motors.”

Piezoelectricity is the ability of some materials (notably crystals and certain ceramics, including bone) to generate an electric potential in response to applied mechanical stress. This may take the form of a separation of electric charge across a crystal lattice. The applied charge induces a voltage as high as 10,000 volts across the material. The word is derived from the Greek piezein, which means to squeeze or press. The effect finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultra fine focusing of optical assemblies. Everyday uses include the ignition source for cigarette lighters and push-start propane barbecues.

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