News Release

Bug-propelled submarines

Reports and Proceedings

New Scientist

Writhing bacteria could power micro-robots round your veins

MICROSCOPIC submarines powered by bacteria could zip round the body delivering drugs and zapping tumours, say researchers in Utah who are developing a novel biomotor.

Earlier this month, the team presented their ideas at the Foresight Conference on Molecular Nanotechnology in Bethesda, Maryland. The motor would be ideal for navigating round the human body, says co-designer Eldrid Sequeira, a nanotechnology researcher at Utah State University in Logan. In scenarios reminiscent of the movie Fantastic Voyage, researchers eventually hope to send robots round the body in the bloodstream to attack tumours with potent drugs or scour out blocked arteries.

Other groups are also trying to make tiny subs, but with alternative power supplies. A company called MicroTEC of Duisburg, Germany, for example, hopes to use an external magnetic field to propel its craft around the body.

The Utah team plan to attach swimming bacteria cells to vanes mounted on top of a silicon disc sealed inside a tiny liquid-filled cylinder. Their natural movement would push the disc around, turning a shaft and generating mechanical energy. With bacterial cells as the power source the motors would only have to be a few tens of micrometres wide.

Later, the team hopes to build biomotors using only the bacteria's flagella and their drive mechanisms (see Diagram). By ditching the unneeded parts of the cells, they could shrink down the biomotors to the 100-nanometre range and run even smaller robots in the future.

At the moment the team is simulating their biomotor on a computer to maximise the power output of their design. But they hope to start building a prototype within a few months. They are focusing on a wild strain of Salmonella typhimurium because of its efficient mobility and relatively long lifespan of about an hour without food.

However, they are still hunting for bacteria with even more favourable traits. Sequeira says that feeding the bacteria to extend their life is not an option, because reproduction would gum up the system. However this wouldn't be an issue if only the flagella were used.

Leslie Rubinstein, president of engineering design firm Renaissance Technologies, based in Lexington, Kentucky, hopes to begin building medical robots in the millimetre range within a year. "It's potentially viable, there's no doubt about that," he says of the biomotor idea. It's not the only option though, other teams plan to harness bacterial chemical reactions for power. This might make biological components unnecessary.

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Author: Mark Schrope, Virginia

New Scientist issue: 25th November 2000

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