Scientists give artificial fingers and hands 'extra feeling'

London, Sept 25 : People fitted with artificial hands will not only be able to sense touch, but would "instinctively" stop objects slipping from their grasp, all thanks to a group of researchers, who have developed sensitive limbs and fingers for making artificial limbs more and more life-like.

Scientists at University of Southern California, Los Angeles, have developed artificial hands and fingertips that have the power of touch and can "instinctively" stop objects slipping from their grasp.

Human hands make use of a built-in reflex that automatically estimate the minimum force needed to hold on to an object.

The reflex works by responding to tiny vibrations in the skin as an object starts to slip through our fingers.

However, the reflex mechanism is missing in existing artificial hands, thus operators have to consciously estimate the required force.

"It's very mentally taxing," Telegraph quoted Jeremy Fishel, a member of the research team, as telling New Scientist.

The researchers have developed a system in which the finger tips consists of a rubber skin, filled with thick silicon gel.

If an object begins to slip, the vibrations in the finger's elastic skin transmit through the silicon gel to sensors attached to a central acrylic "bone".

The vibration provides instant feedback, telling the motors in the hand to tighten their grip before the vibrations stop.

The bone of the finger is also covered with tiny electrodes, across which a small voltage is applied.

The deformations in the elastic skin caused by holding an object alter the distribution of gel in the fingertip, which changes the amount of electricity that is conducted between the electrodes.

The information could then be transmitted to a pressure device worn on a patch of the hand-operator's healthy skin, helping them to "feel" what their prosthetic hand is touching.

A prototype of the finger will be presented at the BioRob conference in Scottsdale, Arizona.

ANI