Miniscule motor swims through the bloodstream

Researchers from Monash University in Australia are working on microbot motors designed to swim through the human bloodstream. Dubbed the "Proteus" after the miniature submarine that traveled through the body in the 1966 sci-fi flick, Fantastic Voyage, the tiny piezoelectric motor is just 250 micrometers or a quarter of a millimetre wide - that's around 2.5 times the width of a human hair.

The motor could be injected into the bloodstream to make current methods of minimally invasive surgery such as keyhole surgery safer and more effective.

Despite the obvious advantages of minimally invasive procedures over cut and sew methods, there is still room for minimizing risk according to research team leader Professor James Friend.

"Serious damage during minimally invasive surgery is however not always avoidable and surgeons are often limited by the width of a catheter tube for example, which in serious cases, can fatally puncture narrow arteries," Professor Friend said.

The micro-motor would carry tiny cameras and sensor equipment and could access parts of the body, like a stroke-damaged artery in the brain, that are beyond the reach of catheters.

To achieve its swimming motion, the vibrating motor is attached to a spiral tail that spins at up to 1295 rpm and acts as a kind of propeller to drive the device forward in a motion similar to that used by bacterial flagella.

Why Piezoelectricity?

Piezoelectricity is the ability of materials like certain ceramics to generate an electric potential in response to applied mechanical stress. Even of you aren't familiar with the term, you've almost certainly encountered the phenomenon in quartz watches and gas stoves. More recently it's been applied in more radical energy saving scenarios like heel-strike generators which farm the energy of footsteps. There's even research underway into roads that harness traffic energy.

In the case of in vivo surgery, Professor Friend and his team chose this as the energy force for their micro motors for two main reasons: it can be scaled down to a level small enough to enter the body and at the same time, it retains enough force to overcome the force of the blood's current.

Prototypes of the motors have been produced the team is working on ways to improve the assembly method and design. The research is outlined in a paper entitled "Piezoelectric ultrasonic resonant motor with stator diameter less than 250 µm: the Proteus motor" which is to be published the IOP Journal of Micromechanics and Microengineering this month.

Via Monash University.