Table 1.

Summary of Relevant Factors Affecting Electrodermal Measurements

Relevant factors	Electrical effects	Important clinical characteristics	Recommended conditions
Stratum corneum	Acts as the greatest contributor to resistance to electrical currents	Skin integrity	Maintain consistent, uniform conditions across testing (i.e., avoid cuts or skin lesions).
		Skin hydration
		Stratum corneum thickness
Sweat ducts	Serve as a shunt for ionic currents	Sweat gland density	Evaluate areas with lower sweat gland density, if possible.
Electrode polarization	Acts as an unwanted capacitor at the electrode-skin interface	Electrode material	Use higher electrical frequencies, nonpolarizable electrodes, larger electrodes. Alternatively, use the four-electrode method.
		Electrode size
		Contact medium
		Current amplitude and frequency
Electrode material	Affects electrode polarizability	Type of electrical measurement	For electrical impedance, use non-polarizable electrodes (Ag/AgCl electrode).
			For electrical potential, use identical materials for all electrodes, active and reference.
Contact medium	Affects electrode polarizability and skin	Dry versus hydrogel versus wet mediums	For dry electrodes, maintain constant pressure and use higher current frequencies.
	Electrical resistance (via skin hydration)	Contact area with skin	For wet electrodes, maintain constant contact medium-to-skin area.
Electrode geometry	Determines current path	Electrode size and shape	Recognize that current density is greatest at smaller electrodes and greater electrode surface convexity
Electrode arrangement	Determines current depth	Distance between electrodes	Decrease the distance between electrodes to study more superficial skin layers. Increase the distance to study deeper layers.