Thirty years later, the idea is no longer just science fiction. Scientists, among them the creators of “Rex” – the world’s most complete bionic man, unveiled in London this week – believe they can now replicate about two-thirds of the human body.

“We were surprised how many of the parts of the body can be replaced,” said Rich Walker, managing director of the robotics team Shadow, who built Rex. “There are some vital organs missing, like the stomach, but 60 to 70 per cent of a human has effectively been rebuilt.” This is heralded, then, as the dawn of the age of bionic man – although specialists caution that we are still feeling our way.

Social psychologist Bertolt Meyer, who also worked on Rex, has an interesting perspective: he was born without his left hand and has a prosthesis. “I have looked for new bionic technologies out of personal interest for a long time and I think that until five or six years ago nothing much was happening,” he said. “Suddenly we are at a point where we can build a body that is great and beautiful in its own special way.”

Not everyone in the field believes the recent progress, impressive as it is, places us on the road to complete replication of human limbs, organs and tissue. “We have motors which can lift things but, if you want to mimic the dexterity of a hand, we are not there yet,” said Professor Steven Hsiao of the John Hopkins University in Baltimore.

“What we are beginning to achieve is building prostheses which look like human body parts, but we are a long way away from making ones which relay sensory information the way the human body does.”

Professor Hsiao drew the comparison between Star Wars and real life, saying: “The goal is the scene in the film where Luke Skywalker gets his new hand tested and is able to feel pain: we are not there. In 10 years, we will be able to build a robot which has the dexterity to pick up a pen and write with it, but it will not be able to send back sensory information.”

Rex, billed as the pinnacle of robotics achievement to date, will meet his public from tomorrow at the Science Museum in London. Dubbed the Million-Dollar Man (that’s how much he cost to make), he consists of a prosthetic face, hips, knees, feet and hands, all of which are commercially available. Other off-the-shelf items include an artificial retina, cochlea and heart.

Rex’s other internal organs, among them a pancreas, a set of artificial lungs and bladder, are still in development. Some of the technology cannot work without human input; bionic hands, for example, need muscles and signals from the brain to function. Other parts, such as the heart and pancreas, are designed to work on their own.

Other body parts remain out of the reach of scientists. Mr Walker says: “The only artificial stomach we have seen is very large and generates electricity, so you couldn’t use it to replace a human stomach, but I am sure there are people in the regenerative medicine community working on that.”

And replication of the human brain, the most complex structure known to man, was not even on the radar, Mr Walker said. “This is a showcase for prosthetic parts, it shows exactly where we’ve got to in being able to replace parts of a human.”

Bertolt Meyer adds: “I’d say it’s highly unlikely that, in our lifetimes or in that of our grandchildren, we will see a fully articulate human body with an artificial intelligence.”

Mr Meyer said there would be ethical issues surrounding prostheses if they began to outperform human body parts. “Should I be allowed to cut off my real hand and replace it with something, does that gives me an unfair advantage over people who cannot afford this? I’m not saying that is going to happen but these are questions that should be on the table before that technology becomes available.”