Touch-sensitive artificial skin may lead to prosthetic limbs which can 'feel'

A newly developed touch-sensitive artificial skin raises the prospect of prosthetic limbs that can "feel".

Scientists showed that the plastic material not only detects pressure but can transmit signals to nerve cells in a laboratory dish.

They hope the proof-of-concept experiment will lead to artificial hands that allow the wearer to feel different textures and distinguish between hot and cold.

The two-ply "skin" has a springy top layer that reacts to pressure and a bottom layer which produces biochemical signals suitable for transmission to neurons.

In the tests, pressure signals from the skin generated light pulses that activated a line of light-sensitive nerve cells.

Other methods of stimulating nerves were likely to be used in real prosthetic devices, said the researchers writing in the journal Science.

Professor Zhenan Bao, from Stanford University in the US, said: "This is the first time a flexible, skin-like material has been able to detect pressure and also transmit a signal to a component of the nervous system.

"We have a lot of work to take this from experimental to practical applications. But... I now see a clear path where we can take our artificial skin."

Attached to a robot hand, the skin was able to detect pressure over the same range as its human counterpart, from a light finger tap to a firm handshake.

The secret of its design is a scattering of billions of carbon "nanotubes" - microscopic hollow carbon rods.

Putting pressure on the skin squeezes the nanotubes closer together and enables them to conduct electricity.

Real skin transmits pressure information as short pulses of electrical signals that are sent to the brain. In a similar way, the artificial skin produces signal pulses that vary in intensity according to the pressure level.