Effective area and charge density of chondroitin sulphate doped PEDOT modified electrodes

Neural electrodes have been coated with electrodeposited poly-3,4-ethylenedioxythiophene doped with chondroitin sulphate. Optical and electrochemical methods were used to determine the effective electrode area, charge injection capacity and charge density of the modified electrodes. Deposition times of 15 to 60 s slightly increased the geometric and steady state diffusion electroactive areas while the linear diffusion electroactive area grew significantly, indicating an increase in electrode roughness. The effective electrode area and charge injection capacity were significantly smaller than PEDOT doped with previously tested dopants. In contrast to other dopant ions, the charge density determined from the geometric and steady state diffusion electroactive areas was nearly constant with increased deposition time while the linear diffusion charge density decreased.