An artificial grasping evaluation system for the paralysed hand

Neuromuscular electrical stimulation (NMES) has been used in upper limb rehabilitation towards restoring motor hand function. Quantitative evaluation of the artificially generated movement is necessary to achieve proper muscle activation. Custom-made gloves instrumented with force and position transducers were used to evaluate artificial quadriplegic grasping for a drinking activity. In spite of different sensor position, stimulation parameter dependence and lack of repeatability, grasp patterns achieved with the application of NMES follow the same patterns previously obtained with normal subjects, regarding force distribution among fingers and the shape of force curves. Larger forces were exerted by the thumb (average ranged from 2.8 to 4.5 N) following by index or long finger (average ranged from 1.8 to 3 N). The forces exerted ranged within the same interval as those previously measured and were sufficient to grasp an object of 10 N. Finger position achieved by interphalangeal joint status indicated the opening size of the hand throughout the range of movement. The instrumented gloves offer an alternative force and position feedback system for use in cylindrical grasp evaluation. The gloves can be used in a closed-loop control system, allowing on-line adjustment or in a clinical application to evaluate the results of a rehabilitation programme.