The present invention is concerned with
functional electrical stimulation (FES) of paraplegics having
spinal cord injuries (SCI), especially for the purpose of walking, where stimulation is applied to motor neurons below the level of the SCI. Specifically, the invention is concerned with FES in closed-loop where
closed loop operation is provided by
wireless feedback by EMG signals recorded via noninvasive surface EMG electrodes. No wire connections are required between the EMG electrodes and a
signal processor (SP) for providing the feedback
signal to the SP. Also, no wire feedback is required to send timing information from the stimulation
signal generator to blocking circuits, in cases where such circuits are required to protect the
wireless transmitters of the feedback information from being damaged by the stimulation pulses.
Wireless operation is facilitated by miniature chips (receivers and transmitters), such as used in the
Bluetooth technology. Hence, the paraplegic users are not burdened with any wires that are otherwise needed for closed-loop operation and with the need to connect them between the patient's back, legs, and a pocket-borne control box. Furthermore,
closed loop operation frees the patients from the need to manually adjust stimulation levels with progression of
muscle fatigue.The present invention allows the achieving closed-loop FES without requiring the sharing the same
electrode for both stimulation and EMG recording and which requires complex control and non-standard electrodes. The avoidance of
electrode-sharing further allows using regular and widely available stimulation electrodes and regular surface EMG electrodes, such as described in Graupe and Kohn: “
Functional Electrical Stimulation for Ambulation by Paraplegics”, 1994.In certain realizations of the present invention, the blocking circuit discussed above requires no input from the stimulus
signal generator, while such inputs are essential in any
electrode-sharing design since pulse level is highest at the stimulation site. Hence, also no
wireless receiver is required next to the EMG electrodes and no
wireless transmitter is required next to the stimulus
signal generator.In certain other realizations, blocking circuits are not required at all.