Electrochemical skin conductance
Electrochemical skin conductance (ESC) is an objective, non-invasive and quantitative electrophysiological measure of skin conductance through the application of a pulsating direct current on the skin. It is based on reverse iontophoresis and steady chronoamperometry (more specifically chronovoltametry).
Source: Wikipedia — Electrochemical skin conductance (CC BY-SA 4.0)