Polarized electrode with ideal geometry

When polarization occurs at an electrode with nonideal geometry (e.g., when the current is limited by rate of electron transfer or by mass transport), there is a gradient in potential in the solution adjacement to the electrode, and associated with this is a tangential as well as normal component of the current at the electrode surface.13 This causes the equipotential lines to intersect the electrode and the current lines to enter the electrode at angles other than 90°. (In the absence of polarization, or in a polarized electrode with ideal geometiy, the equipotential lines would be parallel to the electrode surface, and the current lines would intersect the electrode at an angle of 90°.)... 

These electrodes can be tested by appropriate software as SIMION [31] or other finite-element based programs. The suitability of the electrodes can be evaluated also by calculating their ability to store ions, in comparison with the ideal quadru-polar hyperboloidal geometry [32], to which the designers of micro traps aspire, and by dedicated experiment. 

This effect is observed in the geometry shown in Fig. 6.7(a) when the cholesteric axis h is homogeneously oriented in the plane of the cell (along x), and an electric field is applied to the electrodes of a sandwich cell along the 2 -axis [37, 81, 82]. In this case, the helical structure, even an ideal one, is incompatible with the planar boundary conditions and splayed and bended regions form near the boundaries. Thus, according to (3.19) the flexoelectric polarization arises in those regions which can interact with the electric field. 

---