Friday, 10 April 2015

Prosthetic Hand Recreates Feeling Of Cotton Bud Touch

Prosthetic Hand – Creation of a Sense of Touch

Invention and technology has given rise to a prosthesis which for the first time helps people who have lost a hand due to amputation or accidents,to recognize a natural sense of touch which is often taken for granted. The sensation is so good that a person who had tried the device commented that on leaving the lab, it felt like leaving his hand at the door.

 For ages, researchers had been working on the creation of a sense of touch for those who could have lost their limbs, with intentions that could help them with the control and sense of embodiment of a prosthetic limb. A group of researchers are ahead of the competition with the completion of a successful trial with many others recruiting people for testing the technologies.

Recent developments have enabled people who have lost their limbs to move a prosthesis and grip objects. The ability to distinguish what is essential in controlling and accepting prosthesis as a part of the body and this was accomplished for the first time by Dustin Tyler, together with his colleagues, at the Louis Stokes Veterans Affairs Medical Centre in Cleveland, Ohio.

Cuff of Electrodes – 3 Main Nerves in Residual Area of Limbs

The team found a means of transmitting long term realistic physical sensation like the feel of a cotton wool ball to two individuals who had lost their hands in an industrial accident.

There have been several attempts in creating a sense of touch in recent years by conveying vibration to a person’s residual limb which can equate to pressure on the prosthesis though it proved to be more distracting rather than helpful and has not been adopted.

Attaching electrodes to the inside of residual nerves was also attempted though the tingling sensation produced diminished over a period of time. Something more complex was then attempted by Tyler’s team and two years ago, a cuff of electrodes around the three main nerves in the residual area of the two person’s limbs was implanted which are the nerves that usually transmits sensory information from the hand to the brain.

Each of these cuff comprised of electrodes which could stimulate different parts of the nerve and the wires that were connected with the electrodes to the machine provided a stream of electrical pulses which was connected to the prosthesis used by the individuals. The system was to operate it, wirelessly.

Real Achievement – Prosthetic Limb 

Tyler states that `as soon as they stimulated the nerves in the first subject he immediately informed that for the first time he felt his hand since it was removed’. The team than switched on each electrodes in turn and the individuals felt a tingling sensation as though it was coming from the tip of their prosthetic thumb then the tip of the index finger till the touch sensation moved across the whole of their prosthetic limb.

 Providing a real sense of touch to one who could have lost their limb is a great achievement and doing the same for one who has been paralysed by spinal cord injury could be more challenging wherein a spinal injury could prevent nerves from coordinating with the brain. Hence communication between the brain and prosthetic limb could bypass these nerves.

A team at the University of Pittsburgh, Pennsylvania in 2012 had implanted a device in the brain of paralyzed women, from the neck downwards to help her to control the most sophisticated prosthetic arm with the use of her mind.

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