Figure 3: EMG-controlled FES instrumentation A surface electrode picks up the EMG signal and stimulates the target muscle in proportion to the integrated signal. The EMG signal sensitivity is obtained and the electrical stimulation range is set. This device induces greater muscle contraction because electrical stimulation is proportional to the EMG signal. The EMG-controlled FES unit is an auto-driven system without an on-off switch; therefore, no more operation was required after it had been initially set.