Electric field distribution in the tetrapolar cells. Woodward's cell, (b) tetrapolar cell with flat electrodes, and (c) low EEI cell. All figures have been color-coded according to the scale showed in (d). For a better visualization, the field scale was clipped to a maximum of 2 V/cm. However higher values (~3.5 V/cm) were observed close to the outer electrodes in (a) and close to the acrylic corners in (c).