Prosthetic System with Electrode Cuff Restores Sense of Touch for Amputee
A prosthetic system being developed by researchers at Case Western Reserve University and the Louis Stokes Cleveland Veterans Affairs Medical Center has given amputee Igor Spetic sensation in his hand, after losing it in an industrial accident a few years ago. The system uses electrical stimulation to give the sense of feeling, but there are key differences from other reported efforts. The nerves that used to relay the sense of touch to the brain are stimulated by contact points on cuffs that encircle major nerve bundles in the arm, not by electrodes inserted through the protective nerve membranes. Three electrode cuffs are in Spetic's forearm, enabling him to feel 19 distinct points. When the researchers began the study, the sensation Spetic felt when a sensor was touched was a tingle. To provide more natural sensations, the research team has developed algorithms that convert the input from sensors taped to a patient's hand into varying patterns and intensities of electrical signals. The sensors themselves aren't sophisticated enough to discern textures, they detect only pressure. The different signal patterns, passed through the cuffs, are read as different stimuli by the brain. The system has worked for two and a half years for Spetic, whereas other research has reported sensation lasting one month and, in some cases, the ability to feel began to fade over weeks.