(Invited) Electrochemical Deposition of Conjugated Polymers in the Brain

We have been examining the direct electrochemical deposition of conjugated polymers such as poly(3,4-ethylene dioxythiophene) (PEDOT) into living brain tissue. We use a microcannula to deliver the monomer solution, and a microelectrode to deliver the current. By precisely tailoring and controlling the rate of delivery of the reactants and current, we have shown that PEDOT can be grown out and into tissue for hundreds of microns or more. Our hypothesis has been that this may lead to improved long-term communication between implanted electrodes and the surrounding neural tissue, by creating electrically and ionically conductive pathways across the ~150 um thick reactive glial scar that develops after device implantation. We will discuss our work to investigate this method as applied to electrodes implanted into rat hippocampus, where we showed that electrochemically deposited PEDOT does not cause a significant decrease in the ability of the animal to navigate a maze in a forced alternation task. Most recently, we have been examining the electrochemical deposition of PEDOT in the TEM using a in-situ liquid cell. These studies have revealed previously unseen details about the liquid-to-solid phase transition during the electropolymerization reaction, and have provided clues about how to improve the process in the future.