Electrochemical polymerization of poly(hydroxymethylated-3,4-ethylenedioxythiophene) (PEDOT-MeOH) on multichannel neural probes

Electrochemical polymerization of a derivative of 3,4-ethylenedioxythiophene (EDOT), specifically hydroxymethylated EDOT (EDOT-MeOH) which exhibits higher solubility in water than EDOT, was used to modify the surface of gold microfabricated neural probes. Films of varied thickness of the conducting form of PEDOT-MeOH doped with poly(styrene sulfonate) (PSS) were deposited on the surface of the electrodes using different electropolymerization times. Scanning electron microscope (SEM) images revealed that the surface of PEDOT-MeOH/PSS had a rough and nodular morphology which lowered the impedance of the coated electrode over a wide range of frequencies from 10(0) to 10(5) Hz. At the biologically relevant frequency of 1 kHz, the lowest impedance magnitude was 10 kOmega. Cyclic voltammetry (CV) demonstrated the intrinsic redox reaction and the increased charge capacity of PEDOT-MeOH/PSS coated electrodes relative to the bare gold electrodes. PEDOT-McOH doped with the biologically active nonapeptide CDPGYIGSR was also successfully deposited onto the electrodes to attain adherent and uniform coatings. (C) 2004 Elsevier B.V. All rights reserved.