Microcurrent therapy uses weak electrical currents, similar to those produced by the body's nervous system, to directly stimulate painful or atrophied muscles and acupuncture meridians. This works like massage to relax muscles, calm the nervous system, and improve circulation in painful areas. It is often used to improve wound healing. Microcurrent devices produce a steady, low voltage pulse which causes little sensation as it works. Microcurrent may be used as "electro-acupuncture". Because of the relative freedom from sensation during the treatment, the patient must rely on improvement to know that it is working.