Scientists design device to help those with prosthetics arms to feel touch

Washington: Scientists have designed a novel device to allow those with upper limb prosthetics to feel hot and cold and the sense of touch through their ‘robotic’ hands. Daniel Moran from the Washington University in St. Louis is testing the device that would stimulate the nerves in the upper arm and forearm.

If it works, upper-limb amputees who use motorised prosthetic devices would be able to feel various sensations through the prosthetic, which would send sensory signals to the brain. Mr Moran and his team developed an electrode designed to stimulate sensory nerve cells in the ulnar and median nerves in the arms.

The ulnar nerve, one of three main nerves in the forearm, is the largest nerve in the body unprotected by muscle or bone and is connected to the ring finger and pinkie finger on the hand.

It is the nerve that is stimulated when you hit your elbow on something and trigger your “funny bone.” The median nerve in the upper arm and shoulder is connected to the other fingers on the hand, so together, the two nerves control movements and sensations including touch, pressure, vibration, heat, cold and pain in all of the fingers.

People using arm prosthetics have to rely on their vision to use them properly, Mr Moran said. To pick up a cup of coffee, they have to be able to see the cup, place the fingers of the prosthesis around it and lift it.