Christian Kandlbauer can sense temperature, identify rough and smooth surfaces and feel the strength of a handshake with an artificial hand. This is the first time a prosthesis has transmitted such sensory perceptions back to the brain via nerve tracts: A milestone in the history of prosthetics. The medical technology company Otto Bock HealthCare first presented this groundbreaking further development of the mind-controlled arm prosthesis on Friday, November 27, 2009 in Vienna.
Nerve cords consist of multiple nerve fibres divided into two groups: motor (efferent) and sensory (afferent) fibres. The efferent fibres of a nerve cord are responsible for motor functions while the afferent fibres transmit sensory perceptions in the opposite direction. Now the mind-controlled prosthesis with sensory perception uses both capabilities.
“Micro-sensors that record the temperature, gripping strength and surface characteristics of the object being gripped are integrated into the tip of the index finger on the prosthetic hand,” explains Dr. Hubert Egger, head of the “Mind-Controlled Arm” project.
A microchip “translates” the measured data into suitable stimuli and transmits them to actuators on the skin. These generate natural stimuli for the receptors of the sensory nerve fibres, restoring sensory perception in the brain: As before the amputation, the prosthesis wearer feels with the index finger of the natural hand. “Not only does Christian Kandlbauer move his arm with the image of a natural arm, he has also regained the feeling of the hand,” says Dr. Hans Dietl, CEO of Otto Bock HealthCare Products GmbH in Vienna.
The prosthesis with sensory perception is a prototype. Dr. Hans Dietl expects further development to take approximately four years. Only then will Christian be able to use it on a day-to-day basis. On the other hand, the mind-controlled prosthesis is ready for everyday use. Christian Kandlbauer wears it on the left side. On the right he uses the DynamicArm®, a muscle-controlled arm prosthesis that has proven itself in the market. It captures electric currents generated by muscle contractions using electrodes on the skin and translates them into control signals for the prosthesis. Now 23 years old, the native of Austria had both arms amputated after a high-voltage accident five years ago.
The mind-controlled everyday prosthesis was presented at the Otto Bock Science Center Medical Technology in Berlin on November 13, 2009. With this new development, Christian Kandlbauer is fully independent and pursues his job as a warehouse clerk. He is now driving back and forth to work in his own car. And once again: Alone and without assistance.
The conversion completed by Otto Bock and the vehicle specialist Paravan was presented in Berlin. Technical details of the vehicle include power steering that is especially easy to operate and a fail safe mechanism. This ensures the steering remains easy to operate even in the unlikely event of a motor fault.
But in general, the most distinctive feature of this vehicle is that it is not especially noticeable. At the most, one might notice that secondary functions such as the direction indicator lights, horn and power windows are operated by push buttons and the steering wheel has a handle for the right prosthetic hand.
The newly licensed driver consciously avoided heading directly into Berlin city traffic. But on the streets of Vienna which are just as busy, he headed home to the Steiermark all on his own – from the Museum of Applied Arts (MAK) in the middle of the city.
Did it take a lot of practice to learn how to operate a vehicle with two prosthetic arms? “Of course I had to practice. I completed 26 hours of driver training before taking my test,” Christian Kandlbauer responds. So with two prosthetic arms, he hardly required more hours of driver training than any other beginner.