Patterned Conducting Polymer Microelectronics for Analysis of Neural Signaling

The ion-mediated conduction and versatility of device-fabrication of conducting polymers provide a route to the study of signaling in neural networks. To this end, network patterned junctions of conducting polypyrrole have been electropolymerized on commercially available micro-electrode arrays. The typical dimensions are 200~$\mu$m between electrodes, each electrode being 30~$\mu$m in diameter. Tetrabutylammonium perchlorate or sodium p-toluenesulfonate were used as electrolyte in the organic solvent. Individual polypyrrole junctions, when synthesized and connected in a three-electrode configuration, exhibit current-switching behavior analogous to synaptic weighting or neural ``learning.'' Junctions copolymerized with polythiophene exhibit current rectification and the non-linear current-voltage behavior requisite for neural electronics (\emph{i.e.} the activation function).