Imagine being electrocuted by 20,000V and having both arms amputated when you are just 17 years old and barely old enough to drive. Now imagine driving to work just four years later with a mind-controlled robotic arm. Such is the incredible feat of biomedical engineers at Otto Bock, surgeons at Vienna General Hospital and a 21-year-old Austrian patient named Christian Kandlbauer. The procedure involves a new technique, known as targeted muscle reinnervation (TMR), in which existing nerves that once controlled a lost limb are wired to control a prosthesis.
Surgeons at Vienna General Hospital transplanted the nerves that previously controlled his healthy limb to the chest muscles in a six-hour operation. The transplanted nerves allow electrical impulses from the brain to reach the muscles in the chest. The muscles act like a booster, amplifying the signal to a level that can be picked up by electrodes on the surface of the chest. These signals are interpreted by a micro-computer, and used to control a prosthesis which responds in real time to thoughts from his brain. This allows him to control his prosthetic arm as if it were his real arm. Now Christian can drive, hold down a job, and even grasp a glass of beer.
When phantom limb is ‘moved’, electrical impulses from the brain move along grafted arm nerves into chest wall. Muscles boost electrical sensors and they are picked up by electrodes on surface of skin. Signals analysed and converted into a pattern that can be used to control the prosthetic using artificial intelligence.