Electrochemical deposition and characterization of conducting polymer polypyrrole/PSS on multichannel neural probes

The conducting polymer polypyrrole (PPy) doped with polystyrene sulfonate ( PSS) was electrochemically deposited onto the electrode sites of micromachi ned neural probes. The surface morphology of the films was found to vary wi th coating thickness. Examinations of atomic force microscope (AFM) images of the coatings using the power spectral density (PSD) method revealed the spatial frequency dependence of surface roughness. The magnitude of the imp edance of the PPy/PSS coated electrode at the biologically relevant frequen cy of 1 kHz decreased with increasing thickness as the film roughens. The l owest impedance was observed at a thickness of similar to 13 mum. This decr ease in impedance was correlated to the increase in effective surface area. The power-law behavior of the impedance spectra was quantitatively correla ted with the fractal characteristics of the polymer-coated electrode surfac e morphology. High quality neural signals were recorded acutely from cerebe llum of guinea pig through the PPy/PSS coated electrodes. (C) 2001 Elsevier Science B.V. All rights reserved.