Coating of neural microelectrodes with intrinsically conducting polymers as a means to improve their electrochemical properties

Neural microelectrodes were coated with poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy), using electropolymerization. By electrochemical characterization, it could be shown that the coating led to a significant reduction of the electrode impedance, along with an increase of the charge storage capacity. Electropolymerization was performed under various galvanostatic and potentiostatic conditions, in order to find the optimum parameters. For PEDOT, it was found that the best coatings were obtained for a current density of 1 mA/cm2 or a potential of 0,9 V vs. Ag/AgCl, respectively. The optimum parameters for electropolymerization of PPy were found to be 1 mA/cm2 or 0,7 V vs. Ag/AgCl, respectively. Using optical profilometry, the thickness of the polymer coatings was measured, and a relation between the charge transmitted during electropolymerization and the thickness was determined.