Modern medicine has yielded wonderful advances in cardiovascular surgery, which have saved many lives. Where blood clots or plaque on arteries too delicate for cut and sew operations were once untreatable and ultimately fatal, surgeons can now use catheters to reach many of these locations.
Unfortunately, though catheters have their shortcomings. When navigating narrow arteries, they can sometimes accidentally prick the wall, puncturing it and triggering a fatal bleed. And some areas, like cranial arteries in the brain, are to small and maze-like to reach with a catheter.
Enter the nanobots -- scientists at Micro/Nanophysics Research Laboratory at Australia's Monash University have developed tiny nanobot micromotors that are a mere quarter of a millimeter, powered by tiny piezoelectric motors, capable of swimming in the human bloodstream. They are putting the finishing touches on the motors and readying them for clinical tests on animals and, before long, humans.
While the team is still devising ways to remote control the new robots, they feel that they have a solid solution for an autonomous motor design in the form of piezoelectricity. Piezoelectricity is the ability of devices to generate electric pulses based on mechanical movement or vibrations. Piezoelectric devices include computer's clocks, electric guitar pickups, electric stove lighters, and some inkjet printer heads.
In the human body, the flow of blood provides abundant kinetic energy. While a nanobot is too small to likely have a useful battery, it could exploit this kinetic energy to power tiny micromotors, the goal of the Australian researchers.
Professor James Friend, leader of the research team at Monash University 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 micro-motors."
He says motors have lagged behind other mechanical devices in development, stating, "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."
The new micromotors will allow nanobots to reach places that previous minimally invasive surgery could not, like the human brain.
The team has developed prototypes of the micromotors, which they describe in a journal article found in the Journal of Micromechanics and Microengineering.
The next step is to develop more efficient assembly methods, and to devise ways to control the motors more accurately. The team's work should be a natural fit, though for other researchers' designs, which feature useful arterial nanobots, but lack a system of propulsion. The new work is similar to work by American researchers at Georgia Tech who are working to create blood-powered generators for implants.