Electrochemical polymerization and properties of PEDOT/S-EDOT on neural microelectrode arrays

The conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) doped with its derivative sulfonatoalkoxy EDOT (S-EDOT) was electrochemically polymerized on the surface of electrodes along the shank of microfabricated neural probes. Reflective Fourier transform infrared spectroscopy demonstrated the composition of the resultant polymer. Examinations of scanning electron microscope images of the films indicated that the surface morphology was rough and the thickness varied with deposition time. The magnitude of the impedance of the PEDOT/S-EDOT coated electrode was lower than that of bare gold over a wide range of frequencies from 1 to 105 Hz. The roughness of the electrode surface resulted in a resistive component being added to the double layer capacitance. Cyclic voltammetry demonstrated the intrinsic redox reaction and the increased charge capacity of the PEDOT/S-EDOT coated electrodes.