Interferential stimulator for applying low frequency alternating current

Abstract

An interferential stimulator for applying two medium frequency alternating currents of slightly differing frequencies to the body of a living being so that they cross and interact to produce a low frequency therapeutic current at a selected point. A fixed frequency is generated and applied to the skin through a first electrode pair. A second frequency, differing from the first by from about 1 to 150Hz is applied through a second electrode pair. The electrodes are arranged to deliver a localized stimulation. At the crossing point of the four electrodes a low frequency beat or pulse is produced by the heterodyne process for specific point stimulation. The stimulator may be operated in any of several modes. First, constant stimulation may be applied at fixed frequency difference between electrodes. Second, the frequency difference can be decreased abruptly and returned to the original frequency difference over about 1 second. Third, the frequency difference can be decreased abruptly about 50% and returned over a typically 8 second period. Fourth, a gradual about 50% drop in frequency difference may be accomplished gradually and returned over typically a 10 second period. This device has been found to be useful in reducing pain, and appears to provide benefits in reducing edema and inflammation, increasing blood flow and reducing muscle spasms.