Electrochemical deposition and characterization of poly(3,4-ethylenedioxythiophene) on neural microelectrode arrays

Abstract

The interface between micromachined neural microelectrodes and neural tissue plays an important role in neural recording in vivo. Electrochemical polymerization was used to optimize the surface of the metal electrode sites. Poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(styrene sulfonate) (PSS) was electrochemically deposited on the microelectrodes of neural probes from aqueous solution. The PEDOT/PSS coating decreases the impedance modulus by almost two orders of magnitude. An equivalent circuit model was adopted to analyze the electrical characteristics of the deposited film. Impedance data support an open, fuzzy film morphology that is also demonstrated in SEM images. This open structure shortens the effective diffusion length and allows fast ion transport across the film. In comparison with a previous study on polypyrrole, PEDOT demonstrated much better electrochemical stability. The bioactive peptide DCDPGYIGSR was incorporated in the PEDOT film during the electrochemical polymerization from the solvent mixture of acetonitrile/H 2O (1:1). PEDOT/DCDPGYIGSR coated probes were cultured with rat glial cells and preferential growth of cells was seen on the coated area of the probes. High quality acute neural recordings can be obtained through PEDOT/DCDPGYIGSR coated electrodes.