Fabrication and Characterization of Tunable Conducting Polymer Micro- and Nano-Structures for Bioelectronics

The three novel investigations comprising this dissertation focus tightly on detailing the relationship between conditions of electrochemical deposition and the properties of the resulting CP films or microstructures. The first project elucidated the quantitative relationships between electrochemical deposition parameters and the surface nanostructure of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(pyrrole) (PPy) films doped with poly(styrene sulfonate) (PSS), and demonstrates how physical and electrical properties can be reliably tuned through adjustments of deposition parameters. By developing a model of how CP film properties can be controlled by their deposition parameters, a “toolbox” of sorts may be developed to ensure that PEDOT and PPy components in neural interface applications can most easily possess the most optimal parameters for their intended application. The second project built upon some of the relationships discovered in the first, moving away from classical electrochemical “bath” modalities and using a hydrogel mediator to allow for greater spatial freedom in electrodeposition of PPy:PSS films. Leveraging the relationship between deposition time and resultant film properties created a technique by which PPy:PSS films could be created with surface properties that change over the length of the film. Linear and non-linear gradients of surface roughness were created, and are intended to synergize with the known influence of chemical gradients on axonal guidance. The third project is a further refinement of the hydrogel modality into a system by which PPy:PSS can be electropolymerized in-situ along a path. Known informally as the “gel pen”, this system behaves somewhat like a conventional 3d printer, and it incorporates all the film-property-control lessons learned from the previous two projects. Using commercial software, rather than ad-hoc solutions as in prior projects, this system can accept and execute arbitrary design files.