According to traditional Chinese medicine, a form of bodily energy called chi is generated in internal organs and circulates throughout the body, forming paths near the surface of the skin called meridians. This whole-body network is called the meridian system.  Acupuncture points are points on the skin, usually located on meridians, where the circulation of chi can be manipulated.

By stimulating an acupuncture point on the skin through pressure, suction, heat, or needle insertion, the circulation of chi is affected, which in turn affects related internal organs. But this is not the only way to take advantage of the meridian system. The meridian energy flow also carries with it information about internal organs that can be used in diagnosis. This is the basis of the electrodermal screening test (EDST). The device used in the EDST is the electrodermal screening device, or EDSD, which works by measuring electrical resistance and polarization at acupuncture points and meridians. Through these safe, skin-level measurements, it is possible to analyze the bio-energy and bio-information produced by internal organs and systems.