During clinical evaluation of the limb at RIC, Jesse Sullivan, a patient of Dr. Kuiken, demon-strated substantial improvements in functional testing, such as the ability to reposition his thumb for different grips, remove a credit card from a pocket, stack cups while controlling his grip force using sensory feedback verses vision, and to walk using the free swing mode of the limb for a more natural gait. Harshbarger says that critical to Proto 1's development was closely working with patients such as Sullivan to help the team understand the attributes patients look for in new prosthetic limbs. The limb system also includes a natural-looking artificial covering that was created using photographs of the patient's native limb taken before the accident.

"The Rehabilitation Institute of Chicago continues to advance this applied research and bring the application of the Targeted Reinnervation technique to the forefront to benefit our nation's service men and women," says Dr. Kuiken, the director of the Neural Engineering Center for Bionic Medicine at RIC. "The results we are achieving in this highly collaborative project are very exciting and I am confident that these discoveries will bring more natural control of prostheses, better artificial limbs and make a difference in the lives of amputees worldwide."


More Advanced Prototype Within Reach
APL, which was responsible for much of the design and fabrication of Proto 1, and other team members are already hard at work on a second prototype, expected to be unveiled in late summer. It will have more than 25 degrees of freedom and the strength and speed of movement approaching the capabilities of the human limb, combined with more than 80 individual sensory elements for feedback of touch, temperature, and limb position.

"There is still significant work to be done to determine how best to control this number of degrees of freedom, and ultimately how to incorporate sensory feedback based on these sensory inputs within the human nervous system," Harshbarger says. "The APL team is already driving a virtual model of Proto 2 with data recorded during the clinical evaluation of Proto 1, and the team is working to identify a robust set of grasps that can be controlled by a second patient later this year."

Another exciting development is the functional demonstration of Injectable MyoElectric Sensor (IMES) devices-very small injectable or surgically implantable devices used to measure muscle activity at the source verses surface electrodes on the skin that were used during testing of the first prototype.

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