EMG controlled grasping neuroprosthesis for high lesioned tetraplegic patients

A three channel functional electrical stimulation system with surface electrodes was developed and tested to give complete C4 and C5 tetraplegic patients the possibility of grasping. The neuroprosthesis is controlled by activation of the con-tralateral deltoid muscle. The EMG signal of the voluntary controlled muscle, e. g. deltoid muscle, was amplified, filtered and rectified. The amplitude of the processed signal controlled the pulse dura-tion of the electrical stimulation for finger extensors and flexors and thumb flexors. The benefits of this system are: 1) restoration of the lost function of grasping; 2) natural and easy trainable control of hand opening and closing; 3) smooth adjustment of grasping force; 4) the system takes the advantage of human control; 5) easy integration in a micro-controlled device. Functional tests with C4 to C5 complete tetraplegic patients showed that there is a improvement in the independence of the patient for everyday tasks. The limitations of the system are not the fatigue of finger flexors and extensors, but the fatigue of the voluntary controlled arm movements. For C4 to C6 complete tetraplegic patients grasping neuro-prostheses offer more functionality and independence and therefore the acceptance of such a device can be expected