Over the last several years our group has focused on optimization of conducting polymer modified electrodes for use in biomedical applications. To date we have made substantial progress in three areas: detection of dopamine in the presence of interferents such as ascorbic acid, development of high impedance interfaces for stimulation and interfaces characterized by low impedance at the frequencies relevant for biosignal sensing. In addition to their electrochemical and electrical characteristics, we also have explored the tissue response to the electrodes.  Poly-3-methylthiophene electrodes have proven promising in our solution studies of fast-scan cyclic voltammetric detection of dopamine, both in pH 7.4 buffer and in artificial CSF, with concentrations of 1 micromolar being easily detectable above background. Electrodes have also been produced with both high and low impedance interfaces, with the difference between the two appearing to be a function of the deposition kinetics (in turn a function of such variables as electrodeposition potential profile, concentration, and surface pretreatment. The resulting morphology can be tuned for smooth (features on nanometers scale), smooth with an overlayer which is macroporous (features on order of a micron) or macroporous throughout. These result in high impedance, low impedance (down to about 1 Hz), or impedance typical for a metal with porous coating, depending on synthetic parameters. Conditions have been identified which result in sensing electrodes with a significantly higher signal throughput at low frequencies as exhibited in a rat model for epilepsy. The tissue response to the electrodes has been explored in a rat model and two polymers have been identified which result in a statistically significant (p< 0.05) lower astrocyte buildup near the electrode track.

Conducting polymer electrodes: Significant improvements for analysis and sensing

244th National Meeting (2012)

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