Touch of genius

The Six Million Dollar Man may have been a fictitious character on a show of the same name, but advances in modern bionics have brought the concept of using technology to rebuild human limbs a step closer to reality.

Scientists in the US have reported that advances in bionic hands have restored a sense of touch to two patients. The men can now delicately pluck the stalks out of cherries, it is claimed.

Sensors on the artificial hand are used to send signals directly to the nerves, the study, published in Science Translational Medicine, said.

And, a Swedish team has made a separate breakthrough in artificial limbs - anchoring bionic arms directly on to the bone to improve control.

One of the beneficiaries of the American work was Igor Spetic, who lost his right hand in an accident four years ago.

He was fitted with a bionic replacement, but it was incapable of the sense of touch. He had to carefully watch what he was doing and judge by eye whether he was squeezing too hard.

A team at Case Western Reserve University attached sensors to the bionic hand and in surgery fitted ‘cuffs’ around the remaining nerves, which were capable of delivering electronic stimulation.

The team could send different patterns of electronic stimulation to the nerves using a computer. These were interpreted in the brain as different sensations.

The team mapped these sensations to 19 different locations on the hand, from the palm to the tip of the thumb, and matched the sensors to the different electronic patterns of stimulation.

They then moved on to pressure and textures. Mr Spetic can tell, while blindfolded, whether he is handling different materials such as Velcro or sandpaper.

He has been using the sensing hand for two-and-a-half years. Another patient has been using the system for one and a half years. “At first, it just felt like electrical tingles,” Mr Spetic said.

But as researchers adjusted the pattern and intensity of those signals, he started to feel pressure in his missing fingers, and even different textures.

The real test was when the men tried plucking grapes and cherries from their stems. Blindfolded, they crushed a lot of fruit until the sensory feedback was switched on and they could gentle their grasp.

“We can change what they’re feeling and how they’re feeling it,” said Case Western biomedical engineer Dustin Tyler, who led the research.

“It’s working by reactivating dormant areas of the brain that produced the sense of touch for that hand,” he said.

“They can do really fine delicate tasks now. We believe within five to 10 years we will have a system completely implanted so we would see a person in the morning, they would have the procedure to put electrodes on each nerve and a device for their pocket, so that when they turn it on they can feel their hands.”