Metrological analysis of three-electrodes method of skin conductance measurements

Physiological interpretation of the electric parameters of the skin is difficult due to the influence of many factors both endogenous and exogenous. The method using 3 electrodes is widely renowned in psychological research. The paper evaluates the influence of real parameters of the operational amplifier on skin conductance measurement errors. Theoretical analysis indicates that the amplification coefficient of the constant voltage amplifier being the main element of the whole system is a parameter determining the electrodes arrangement in the 3-electrodes method of the skin conductance measurement. The current error of the system is minimal when the distance between the measuring one E_M and the referential E_R electrodes is much smaller in relation to the distance between the referential E _R and current electrode E_C. In order to determine the right arrangement of the electrodes we can make use of the output voltage signal level as well as the output capacity of the system treated as a current source