In a typical test, the sample is placed in contact with two electrodes (the dielectric sensor) and a sinusoidal voltage (the excitation) is applied to one electrode. The  resulting sinusoidal current (the response) is measured at the second electrode.
A standard test involves placing a sample between two electrodes (the dielectric sensor). A sinusoidal voltage is then applied to one of these electrodes, generating a corresponding sinusoidal current (the response) that is measured at the other electrode.