A range of complex surgical operations necessary to treat stroke
victims, confront hardened arteries or address blockages in the
bloodstream are about to be made safer as researchers from the
Micro/Nanophysics Research Laboratory at Australia's Monash University
put the final touches to the design of micro-motors small enough to be
injected into the human bloodstream.
ImageA research paper, published today, Tuesday, 20 January, in IOP Publishing's Journal of Micromechanics and Microengineering
details how researchers are harnessing piezoelectricity, the energy
force most commonly used to trigger-start a gas stove, to produce
microbot motors just 250 micrometres, a quarter of a millimetre, wide.
of minimally invasive surgery, such as keyhole surgery and a range of
operations that utilise catheters, tubes inserted into body cavities to
allow surgical manoeuvrability, are preferred by surgeons and patients
because of the damage avoided when contrasted against cut and sew
operations. Serious damage during minimally invasive surgery is however
not always avoidable and surgeons are often limited by, for example,
the width of a catheter tube which, in serious cases, can fatally
puncture narrow arteries.
Remote controlled miniature robots
small enough to swim up arteries could save lives by reaching parts of
the body, like a stroke-damaged cranial artery, that catheters have
previously been unable to reach (because of the labyrinthine structure
of the brain that catheters are too immobile to safely reach). With the
right sensor equipment attached to the microbot motor, the surgeon's
view of, for example, a patient's troubled artery can be enhanced and
the ability to work remotely also increases the surgeon's dexterity.
Professor James Friend, leader of the research team at Monash
University, explained, motors have lagged behind in the age of
technological miniaturisation and provide the key to making robots
small enough for injection into the bloodstream. "If you pick up an
electronics catalogue, you'll find all sorts of sensors, LEDs, memory
chips, etc that represent the latest in technology and miniaturisation.
Take a look however at the motors and there are few changes from the
motors available in the 1950s."
Professor Friend and his team
began their research over two years ago in the belief that
piezoelectricity was the most suitable energy force for micro-motors
because the engines can be scaled down while remaining forceful enough,
even at the sizes necessary to enter the bloodstream, for motors to
swim against the blood's current and reach spots difficult to operate
Piezoelectricity is most commonly found in quartz
watches and gas stoves. It is based on the ability of some materials to
generate electric potential in response to mechanical stress. In the
case of a gas stove, the ignition switch on a stove triggers a spring
to release a ball that smashes against a piece of piezoelectric
material, often kinds of crystal, which translates the force of the
ball into more than 10,000 volts of electricity which then travels down
wires, reaches the gas, and starts the stove fire.
Professor Friend explains, "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. Piezoelectric designs however have
favourable scaling characteristics and, in general, are simple designs,
which have provided an excellent platform for the development of
The team has produced prototypes of the motors
and is now working on ways to improve the assembly method and the
mechanical device which moves and controls the micro-motors.