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Thursday, November 15, 2012

The world's first mind-controlled implantable robotic arm

Credit: Chalmers, Max Ortiz Catalan
The world's first implantable robotic arm controlled by thoughts is developed by researcher Max Ortiz Catalan, at the Department of Signals and Systems, Chalmers University of Technology in Gothenburg, Sweden, and at Integrum AB. This winter the first patients will be operated with this revolutionary device.
Every year thousands of people around the world lose an arm or a leg. With the new technology patients will get a brand new and mind controlled body part.
Ever since the 1960s amputees have been using prostheses that are controlled by electrical impulses in the muscles, but the technology for controlling prostheses has not evolved much since then. For example there are very advanced electric prosthetic hands, but they are not used as much because they are so difficult to control. All movements must be pre-programmed, says Max Ortiz Catalan. It's like having a Ferrari without a steering wheel. The researchers at Chalmers have therefore developed a new control system from scratch. The usual prostheses are fixed directly to the skin surface of the amputated stump, which is so uncomfortable that only 50 percent of the amputees are willing to use them. In this research project the prosthesis is anchored directly into the human skeleton with the world-famous Brånemark screw, so-called osseointegration. Osseointegration is crucial by employing implantable electrodes permanently accessible through the Osseointegrated Human-Machine Gateway (OHMG). The OHMG is a bidirectional interface that allows permanent communication into the human body, and it is the key development of this project.
Mind controlled prosthesis
To obtain the electrical impulses to control the prosthesis electrodes has been previously attached outside the body to the skin. The problem is that the impulse change when the skin is involved, since the electrodes are then moved to another position. The impulses are also affected if the patient sweats. In this project, researchers are implanting electrodes directly on the nerves inside the body. The body protects the electrodes and electrical impulses are more stable. Osseointegration is used to receive signals from within the body to the prosthesis. The electrical impulses from nerves in the arm stump are caught up in the OHMG interface inside the titanium screw, which enhances and transfers impulses to all parts of the prosthesis. It allows a patient to control the prosthesis in a more natural and intuitive way.
From the lab to the patients
Many of the patients in the project have been amputated for more than ten years and have never touched their hands during that time, says Max Ortiz Catalan. When they came to the lab they had to test a virtual reality environment to evaluate the researchers technical algorithms. They got electrodes on their amputation stumps so that they could control more advanced prosthesis. This made the patients very enthusiastic. By testing the method on some patients, the researchers could show that the method works, and will now go further with clinical trials and development of the method.
Check out the video demo below of controlling an arm in a virtual environment.

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