A Transcutaneous Electrical Stimulation Method for Sensory Substitution of Wrist Extension and Flexion - a preliminary study

Abstract

mong the need of improvement of the sensory function in myoelectric prosthesis, this paper focuses on the position sense substitution of the prosthetic wrist joint. The study proposes a transcutaneous electrical stimulation method by using the superficial skin sensation to replace the position sense of the prosthesis wrist, and makes amputees sense the flexion and extension of the prosthetic wrist. The study uses a combination of spatial and intensity encoding to map the evoked spatiotemporal patterns of superficial skin sensations to three types of wrist positions by applying a combination of different current amplitudes to two stimulating electrodes placed on the skin of the upper limb. The experimental paradigm of the learning and re-learning stages and the experimental paradigm of the testing stages are designed. One able-bodied subject and two amputee subjects are recruited to verify the feasibility of the method. The overall recognition rate of able-bodied subjects, transcradial amputee subject and transhumeral amputee subject is 84.4%, 73.3%, 48.3% respectively. After learning and re-learning, the recognition rates of subjects improved significantly. The results show that the method is simple and feasible, and can allow the subjects to perceive the prosthetic wrist flexion and extension state, as well as increase the information transfer between the prosthesis and amputees to improve the acceptance of the prosthesis.