UC Irvine

With incidents of stroke becoming increasingly frequent, finding new means of providing more efficient and effective rehabilitation has become a rapidly growing area of research. While much of the focus has been directed towards robot-based methods, mechanically passive methods capable of providing similar therapeutic benefits in a less expensive and safer package are also being explored. Such devices are more practical for wide-spread use, both in a clinical setting as well as for in-home therapy. This thesis developed a mechanically passive device for neuromuscular rehabilitation after stroke called WRIST (Wrist Resonator for Independent Stroke Training). WRIST incorporates a tone-canceling linkage designed to counteract intrinsic wrist stiffness to ease movement, as well as an appropriately designed mass and superimposed spring stiffness to create a resonant environment that the user can take advantage of to facilitate repetitive wrist flexion and extension. As a proof of concept, a pilot study with two, chronic, severely-impaired stroke subjects was conducted to verify benefits of the linkage and resonant system. The torque profiles of each subject's wrist, as well as the residual wrist torque with the linkage engaged were measured and verified that the linkage accurately cancelled the intrinsic wrist stiffness. Moreover, the tone-canceling linkage increased active range of motion of the wrist, and superimposing the resonant system further increased it. These results support the idea that appropriately-designed, mechanically passive devices have the potential to provide therapeutic benefits similar to that of robotic rehabilitation devices.