Difference between averaged measurements before and after addition of SMV in tetrapolar cells. The horizontal axes stand for the frequency and amplitude of the applied electric field. The vertical axis stands for the amplitude of the third harmonic measured at that combination of frequency and amplitude. The experiment was performed with the flat parallel electrodes cylindrical cell showed in fig. 1(b). Frequency range was 1 Hz~100 Hz (logarithmic scale, 11 steps), and field range was: (a) 0.167 V cm-1 ~1.33 V cm-1 (logarithmic scale, 11 steps). Surface is color-coded according to the color bar presented.