The design of a constant current muscle stimulator

An instrument that produces two constant current sinusoidal signals for use in the treatment of muscular disorders in human patients was designed, developed, and evaluated. The instrument will produce 50mA rms per channel into a patient load at user selectable carrier frequencies of 2.5KHz or 5.0KHz. The instrument provides a beating effect by allowing the frequency of one channel to track the frequency of the other within a range of 1Hz to 200Hz, with the exact point in this range controlled by the user.

The instrument uses analog signal processing circuits to generate and shape the output signals, remove unwanted components, and produce high spectral purity outputs. The instrument provides isolated, constant current output signals on each channel and a maximum treatment time of sixty minutes. The instrument provides a modulated treatment mode which produces an amplitude modulated current signal on each channel to allow treatment of separate locations simultaneously. Circuitry that resets the instrument in the event of a treatment mode change or power failure is included to insure patient safety. Although every effort has been made to insure patient safety, not all possible safety issues have been addressed.