A Bio-feedback Training and Evaluation System for Directional Control of Pinch Force

Hand function recovery is an urgent demand in stroke patients. Pinch with the thumb and index finger is a fundamental form for object manipulation and thus plays a key role in dexterous hand function. To improve the post-stroke hand function, particularly the pinch force control, with low-cost, easy-to-use and customer-friendly training devices would be a desirable direction for hand rehabilitation. This study aimed to develop a novel bio-feedback system integrating both training and evaluation of the directional control of pinch forces. The system included both hardware and software. The effects of the bio-feedback system were examined through an experiment. Twenty-six healthy subjects participated in the experiment. Each subject performed low-level precision pinch with their thumb and index finger for two training sessions and three evaluation sessions. Two visual conditions (with vs. without visual feedbacks) and the two digits (thumb vs. index finger) were considered. Detrended fluctuation analysis (DFA), standard deviation (SD) and the shear to normal force ratio rsn were employed to evaluate the directional control of pinch force. Results validate the effectiveness of the bio-feedback system, which may provide a novel solution for rehabilitation of hand function.