Science, Science and Tech

Reach out and touch

Up until very recently, for those who have had to endure the loss of a limb the best alternatives available have been facsimiles, which are perceived as a poor substitute for the real thing. This measures in strange contrast to science fiction, where those with artificial limbs are usually depicted as being stronger, faster, or more durable than their organic counterparts. Now, however, the gap between fantasy and reality may be about to be breached.

A collaboration between the EPFL (Swiss Federal Institute of Technology) in Switzerland and the SSSA (Sant’Anna School of Advanced Studies) in Pisa. Italy has produced one of the first bionic hands. What makes this hand so special compared to other prosthetics is that, rather than just sitting in place over the end of the wrist and being controlled by muscle contractions in the upper arm, as many current models are, the LifeHand 2 actually connects to the nerve endings which remain in the subjects arm, allowing a computer algorithm to translate the electrical potential impulses from the nerves into mechanical movement.
The LifeHand 2 builds on the technology of its’ predecessor, LifeHand, which used similar technology to become the first thought controlled prosthetic ever. What makes LifeHand 2 so remarkable however, is that it doesn’t juat allow the nerves to send signals to the mechanical fingers; it allows the fingers to send signals back.Each fingertip is coated with pressure sensitive nodes which feed back to four separate electrodes implanted in the median and ulnar nerves. A reverse version of the computer program which allows the nerves to send signals to the hand then transmits the feel of what the hand is touching to the brain, allowing the sensation of touch to be restored.
The first man to test this was Dennis Aabo Sørenson, a Danish man who lost his left hand in a fireworks accident nine years previous. It took three weeks to implant the sensory electrodes into Sørenson’s long defunct nerves, and to ensure they were still operating correctly and were unaffected by scar tissue forming around the implants. Due to regulations however, he was only allowed to use the hand for a month before effectively undergoing a second amputation, though the attending scientists are confident the electrodes could remain in place for years without degrading. The work now will be to refine this technology until Dennis Sørenson can get his hand back for good.


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