Theory of frequency-dependent polarization of general planar electrodes with zeta potentials of arbitrary magnitude in ionic media 1. Theoretical foundations and general results

Electrode polarization effects have long aggravated the efforts of low freq uency analysis, particularly those investigations carried out on biological material or in highly conductive media. Beginning from elementary equation s of electrostatics and hydrodynamics, a comprehensive model is devised to account for the screening of a general planar electrode by an ionic double layer. The surface geometry of the planar electrode is left unspecified to include any type of micromachined array, Building on the previous work by D eLacey and White (1982, J. Chem. Sec. Faraday Trans. 2 78, 457) using a var iational theorem, we extend their numerical results with compact analytic s olutions, analogous to the Debye-Huckel potential for de systems, but appli cable now to dynamic ac experiments. The variational approach generates fun ctions that are not restricted by perturbation expansions or numerical conv ergence, representing optimal approximations to the exact solutions. (C) 20 00 Academic Press.