IF, according to Tim Robbins's character in The Shawshank Redemption, "hope is a good thing, maybe the best of things", then the story that a stroke victim was able to move a robotic arm with the power of thought must give unparalleled optimism to paralysed people the world over.

The mere idea that a tiny chip implant could allow such people to actually move objects – and possibly, in future, even walk again – is the stuff of science fiction.

But for Boston stroke victim Cathy Hutchison, 59, the reality of this scientific miracle played out right before her very eyes. For the first time in almost 15 years, Ms Hutchison, who is normally unable to move any of her limbs, was able to sip a coffee without the help of her carer. And she did it with the use of a mechanised arm as part of a project led by Professor John Donoghue, Dr Leigh Hochberg and the rest of their Brown University and Harvard Medical School research team. Watching such a miracle was, they said, a moment of "pure joy". That and the culmination of decades of research.

So how did they do it? The electronic chip that was implanted in her brain, allowing her to perform such a feat, is called a BrainGate chip. Apparently no bigger than a small aspirin tablet – comprised of a grid of electrodes – the chip is placed in the part of the brain that controls movement. When patients think about moving their arm, the electrodes pick up the signals in their brain and transmit them to a computer system through which a cable is "plugged" into the user's head. The computer does its thing; decodes the signal and send it to the arm; and, hey presto, it moves.

It's all part of research entitled brain-computer interface, or BCI – a branch of research investigating how brains and computers can work together. It's a sector of science with almost limitless possibilities – even mind reading has been mentioned – and it has certainly piqued the interest of many people. The research has, in part, been funded by various government bodies, including the US military and the German Aerospace Centre.

If it all sounds unbelievable, yet familiar, that's because it's reminiscent of something you might see in a Hollywood movie like the Terminator. The fact that a mere microchip could give the power of mind control is baffling for most of us. But the seemingly simple task Ms Hutchison performed in reaching for her morning coffee cup is one that represents so much more. It proves the practical benefit of such an apparatus and, moreover, symbolises the real ambition of the researchers: to harness the power of the human mind to one day allow the paralysed to move their own limbs again.

It's hoped that one day this dream will be a reality and the technology could be used to help a range of people, including those who have lost limbs, people with Lou Gehrig's disease and those with spinal-cord injuries, all whose brains remain totally active, even if their bodies are not. And most importantly, it could be used to help people for whom all hope had seemed lost.

.... the BrainGate chip