It can't click its fingers or play the piano but there's not much else the latest bionic hand won't do.

A massive advance on previous artificial limbs, it can turn a key in a lock, hold a wine glass or punch a pin number into a cash machine.

For $25,000, the wearer gets a hand that, for the first time, bends its fingers to grip objects, said inventor David Gow, an engineer with Lothian NHS in Scotland.

The i-LIMB has a flexible wrist and rotating thumbs. "And it's the first to come to the market that has bending fingers just like your own," said Gow.

Lighter than a real hand, the device capitalises on the brain's determination to try to move a limb even when it has been lost. The brain thinks it is still there and sends signals to the nerves and severed muscles.

These are intercepted by delicate sensors and used to move tiny motors hidden in the artificial fingers. While traditional prostheses have only one motor, allowing limited movement, the i-Limb has five, with one concealed between the base and knuckle of each finger.

Covered in artificial skin, the one-size-fits-all hand has already won the approval of patients on both sizes of the Atlantic, including Iraq war veterans.

Father-of-two Juan Arrendondo, was a sergeant in the US army when he lost his hand to a roadside bomb in 2004. He tried several other artificial hands before settlingon the i-LIMB. The 27-year-old-from Texas said: "Now I can pick up a Styrofoam cup without crushing it.

"With my other hand, I really had to concentrate how much pressure I was putting on the cup. Every day I have this hand, it surprises me."
The device is on sale privately, with an entirely lifelike version for around £13,000. It could be available on the NHS in about three years.

Made from light-weight plastic usually found in car engine components, the hand is attached to the arm via a laminated socket.

The socket, which slips over the patient's arm, conceals a rechargeable battery and a pair of electrodes which sit on top of the skin, where they pick up signals destined for the absent hand.

The signals are transmitted to a tiny computer housed in the back of the artificial hand and controls the motors hidden in the fingers.

Small objects such as coins can be picked up between the index finger and thumb, while other grips allow turning a key in a lock, holding a plate and handing over a business card.

So flexible are the fingers that they can open the ring-pull of a soft drink can. Best of all, the wearer doesn't have to do the washing up as it's not totally waterproof.

Phil Newman, of Touch Bionics which developed the hand at Livingstone, Lothian, said: "For someone born without a hand, seeing their fingers moving is very emotional. And very rewarding for us."