PARIS - IN 1966, the movie 'Fantastic Voyage' recounted the tale of doctors who are miniaturised along with a submarine and injected into the body of a Soviet defector, sailing up his bloodstream to destroy a brain clot that imperils the VIP's life.
The improbable storyline - and the equally improbable casting of sex icon Raquel Welch as a scientist in a wetsuit - invited the audience to suspend their disbelief and enjoy a good sci-fi romp.
More than 40 years later, some of the futuristic potential of 'Fantastic Voyage' has taken a step closer to realisation, thanks to a remarkable achievement in miniaturisation unveiled on Tuesday.
There's no submarine or Raquel Welch, but instead a motorised robot that its inventors believe is small enough to be injected into the human bloodstream.
One day, the remote-controlled bot could carry sensor equipment for observation work, relaying images back to surgeons.
Or it could become a tiny surgeon, cutting away blood clots, reaming out clogged arteries or repairing damaged tissue, its inventors hope.
The 'microbot' measures just a quarter of a millimetre, or 'two or three human hairs wide,' said lead scientist James Friend, from the Nanophysics Laboratory at Monash University, Australia.
'We are looking for something that can be placed in human arteries, especially in locations where it can't be done with the technologies that were around previously,' he told AFP.
Conventional methods of 'keyhole' and other minimally invasive surgery today use tubes called catheters, which are inserted into body cavities and arteries.
But catheters are rigid and despite their small size can still puncture thin arterial walls.
In a paper published in the peer-reviewed Journal of Micromechanics and Microengineering, Friend's team describe prototype work on a motor based on piezo-electricity, the energy used in quartz watches, upmarket cigarette lighters and gas-stove lighters.
Piezo-electric materials are ceramics or crystals that generate a voltage in response to mechanical stress.
In this case, the materials vibrate a corkscrew-like microstructure inside the bot that then drives a 'propellor' comprising soft flagella.
Like a swimming bacterium - but guided externally by remote control - the robot would make headway against the bloodstream, at least in blood vessels where the flow is not too great, the inventors hope.
The device could transmit images, deliver microscopic payloads and, eventually, carry out surgery, said Dr Friend. It would then be retrieved by syringe at the point of entry.
'For the moment, we are going for observation, because it is the easiest thing to do,' said Dr Friend. 'From that point on, we will go for other kinds of operations, mainly snipping and cutting.' If the device breaks down, it would return downstream to the point of entry and then be picked up, or it could be recovered by micro-catheter, he said.
The team has produced prototypes of the motors and is now looking at how to improve the assembly method and a mechanical device that moves and controls the micromotor.
But years of work probably lie ahead before it is used on a human patient.
In a link with 'Fantastic Voyage,' the microbot has been baptised Proteus, carrying the same name as the miniaturised sub in the movie.
The moniker was chosen by readers in a 'name-that-bot' poll on the technology website Wired, said Dr Friend. -- AFP