Impeto Medical patented technology measures the capacity of the autonomic sweat glands to release chloride ions in response to an electrochemical stimulus.  It is a dynamic test. 
A low voltage potential of variable amplitude is applied to sensors on regions of the skin with a high density of sweat glands (hands and feet) to stimulate the sweat glands, extract chloride ions and produce a current. This ensures that measurements correspond to the local sweat function. The technology provides a quantitative measure of chloride sweat conductance (measured in microsiemens) and its results serve as a biomarker to assess sweat gland function in relation to sweat gland innervation.