Modeling Multi-Scale Carbon Fiber Supports for Thin Film Bioelectrodes

Carbon electrodes with their super electro-catalytic properties are commonly used in electrochemistry, especially in biomolecular redox reactions¹. Electrospinning as a low cost, facile technique is applied to produce uniform carbon nanofibers between 150 nm and 1µm fiber diameter by pyrolyzing electrospun Polyacrylonitrile (PAN) fiber at 250°C and 1100°C. Varying the concentration of PAN in N,N-Dimethylformamide precursor solution changes the fiber diameter and leads to diversity in materials properties, such as surface area, void fraction and conductivity. These electrospun carbon nano fiber (ECNF) properties are characterized by SEM, BET, and four-point probe resistivity measurements.

 Thin film Os^+/2+ mediated electron in hydrogel immobilized glucose oxidase layer is coated on either single micro fiber ² or free - standing carbon nanofiber mats (Figure 1) to study the effect of carbon fiber physical properties on electron transfer in mediated redox hydrogel bioanode. Electron transport via redox polymer Os^+/2+ is enhanced by reducing the average hydrogel film thickness with uniform distribution of small fiber of high surface area (<1.6E3 cm^-1 surface area per volume). A transport model is developed to give more insight into these correlations and yield more understanding of electron transfer mechanism in thin film porous electrode.