The basic concept for all of the ElectroDermal screening devices, was the invention of Dr. Reinhardt Voll
[1], who in the 1940s, discovered that the electrical resistance of the human body is not homogenous and that meridians existed over the body which may be demonstrated as electrical fields. Furthermore, he showed that the skin is a semi-insulator to the outside environment. By the 1950s Voll had learned that the body had at least 1000 points on the skin which followed the 12 lines of the classical Chinese meridians. Each of these points, Voll
[2] called a
Measurement Point (MP). Working with an engineer, Fritz Werner, Voll created an instrument to measure the skin resistance at each of the acupuncture points, patterned after a technique called
Galvanic Skin Resistance (GSR). This was named Point Testing. In 1953, Voll had established the procedure that became known as Electro-Acupuncture according to Voll
(EAVJ. This included two parts:
1.[FONT="] [/FONT]The first part was point testing in which a conductance measurement was taken in selected acupuncture points.
2.[FONT="] [/FONT]The second part was the establishment of a balance of the points and conductance by the use of feedback medicine. This became known as Medicine Testing.
During the 1950s, many investigators
[3] including Nakatani studied the electrical conductance of the skin. They evaluated the elasticity, resistance, permeability, and chemistry among many other properties of the skin and found that there was a much lower skin resistance
(higher conductance) at specific points on the skin. Normally, the skin has a resistance of 2-4 million Ohms but over the specific conductance points, the resistance of only 100,000 Ohms is found in normal healthy persons. These points corresponded to classical acupuncture points.
Later, these acupuncture points were investigated and were considered to be "information access windows" and the assumption was made that the health status of an organ will affect the concentrations of the ions at the measurement points along the meridian
(measurement points). It was considered that inflammation of an organ may cause increase ion concentration and the increase of ions enhances the flow of electrons causing resistance to decrease while the conductance may increase. On the other hand, a degeneration of an organ may cause decease in ion concentration that hinders the flow of electrons, so as the resistance increases conductance decreases.
During the procedure of ElectroDermal analysis the body becomes an integral part of a closed circuit. The conductance circuit touches two areas on the body being tested. In the first point of contact, the ground electrode is held in the palm of the opposite hand to be tested. In the second place the test probe touches the specific acupuncture or conductance points on skin. After completing this closed circuit, a known amount of electric current is emitted from the instrument through the probe. The instrument then measures the conductance from baseline to peak and return to baseline through the conductance point that is being tested by the probe. This represents a dynamic conductance value.