Combining Voltage and Current Control for Efficient Electrical Stimulation

This paper introduces a system architecture with an improved power consumption for functional electrical stimulation (FES). Based on a simple current-controlled stimulator design, an analog control loop is integrated into the feedback loop of the boost converter to manipulate the high-voltage generation. In that way, the output voltage is only as high as necessary to drive any desired pulsed current through tissue with variable impedance. The efficiency for the generation of monophasic stimulation pulses could be improved by about 50 %. Another advantage is the circuit's simplicity. The added voltage control loop has only a few additional components, is easy to understand, and therefor perfect for small, battery operated devices, where runtime is an important factor.