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Tiny twisting muscles developed for propelling nanobots


October 14, 2011

Scientists have created a tiny artificial muscle, that could be used in motors to propel nanobots inside the human body (Image: University of Wollongong)

Scientists have created a tiny artificial muscle, that could be used in motors to propel nanobots inside the human body (Image: University of Wollongong)

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We've been hearing a lot lately about the possibility of treating medical conditions using nanobots - tiny robots that would be injected into a patient's bloodstream, where they would proceed to travel to their targets, not unlike the microscopic submarine in the movie Fantastic Voyage ... except nanobots wouldn't be crewed by tiny shrunken-down humans. One challenge that still needs to be met, however, is figuring out a way of propelling the devices. Well, we may now be closer to a solution. Yesterday, development of a new type of nanoscale artificial muscle was announced, which works like the muscles in an elephant's trunk. These could conceivably be used in nanobots, to whip them along using a rotating flagellum - a tiny sperm-like tail, in other words.

At the heart of the artificial muscle is a strand of tough, flexible yarn made from carbon nanotubes that have been twisted together. It is immersed in liquid electrolytes. When voltage is applied, the yarn draws in electrolytes, causing it to increase in volume. This in turn causes it to untwist itself, rotating at up to 600 revolutions per minute as it does so. If the voltage is changed, the yarn then proceeds to discharge the electrolytes. In doing so, it is able to twist itself back up, rotating in the opposite direction.

In a nanobot equipped with batteries and an electrical circuit, the back-and-forth spinning of such a yarn motor attached to a flagellum could cause the tail to wiggle in circles, pushing the nanobot through its liquid environment. The yarns are reportedly simple and inexpensive to make, and can be created in a variety of lengths.

Elephant trunks and octopus tentacles work using a similar principle, in that they incorporate helically wound muscle fibers that rotate in either direction to move the appendage.

The artificial muscles were developed through a collaboration between Australia's University of Wollongong, The University of Texas at Dallas, The University of British Columbia, and Hanyang University in Korea. A paper on the research was published yesterday in the journal Science.

The video below illustrates how one of the artificial muscles could work in a nanobot.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

@denis... only in a stagnant liquid?

Victor McDermott

So they would go forwards when charged and then backwards when discharged, going nowhere fast!

Denis Klanac

The bot will likely rotate randomly when not moving forward or backwards. This is what bacteria do. The end result is movement in random directions... and bacteria stop and rotate less often when they are in a place they like, and more often when they are not happy yet. This is how they \"get somewhere.\" (At least, this is my non-expert description.)

Melanie Stegman
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