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Monash developing medical micro-robots

22 September 2008

"This is a triple-axis motor, a new design, to actually allow us to do a lot more with our microrobots," said Associate Professor James Friend. "The ball is 1 mm diameter, the wire is gold wire, half the diameter of a human hair."
The Australian Higher Education, Wendy Zukerman | September 17, 2008

MINIATURE robots are being designed to enter the human body and assist with surgical procedures beyond the reach of present technology.

Scientists hope that within the next few years micro-robots will travel through the narrowest blood vessels in the brain, allowing treatment and diagnosis in areas previously thought inaccessible.

Monash University's Micro-Nanophysics Research Laboratory is one of only a few laboratories in the world that has the technology to make this hope a reality.

"Using conventional technology when you have an injury or a blood clot in the brain, to get to the region a surgeon will need to push a catheter through the groin to the brain via the carotid artery," the laboratory's associate professor James Friend explains.

These catheters have curved tips to allow surgeons to manoeuvre their way into affected areas.

"Due to the difficulty reaching certain areas, some 40 per cent of these surgeries fail because, as the surgeon uses the catheters, they puncture the artery.

"As you move around the brain the blood vessels get smaller. If there is an injury in smaller arteries you can't get to them using the curved tip because it's too big.

"But our robots are the size of two human hairs and can fit into these areas."

These micro-robots fit at the tip of a catheter and are connected to a remote control through electric wiring in the catheter.

Surgeons find they can accurately and effectively control the catheter without pushing and pulling, and without a hook.

The most difficult part of Friend's research has been designing miniature motors with enough power to move the robots through the blood in the body. The smaller the object, the more forces required to move it.

"Water behaves like honey on a small scale," Friend says. "A large boat can use a propeller to move it, but a fish needs a fin and, even smaller, E. coli bacterium uses flagella. Flagella motion is the most efficient movement at that size." Flagella are thread-like tails projecting from bacteria that allow mobile bacteria to move.

Using nature as inspiration, Friend's miniature robots can swim through the body because he attaches a flagellum (singular for flagella) to a high-powered rotary micro-motor.

These motors spin flagella and can propel the robots through the fluid. "Our team is unique in the sense that we've been able to get enough torque using our motors to move the robots," Friend says.

Friend's research team plans to design prototypes for wireless micro-robots. "These could swim to the injured area and swim out of the body without any catheters involved," he says.

In the meantime, Friend intends that a complete prototype of the catheter micro-robot will be ready for next year. In 2010 the Royal Melbourne Hospital is preparing totrial this technology for terminally ill patients who cannot be treated conventionally.