text: One conducting polymer coating that has shown promising results for improving the performance of neural electrodes is polypyrrole (PPy). Polypyrrole has great biocompatibility and conductive properties, which makes it a good option for the use in neural electrodes. PPy has been shown to have a good interaction with biological tissues. This is due to the boundary it creates between the hard electrode and the soft tissue. PPy has been shown to support cell adhesion and growth of a number of different cell types including primary neurons which is important in neural implants. PPy also decreases the impedance of the electrode system by increasing the roughness on the surface. The roughness on the electrode surface is directly related to an increased surface area (increased neuron interface with electrode) which increases the signal conduction. In one paper, polypyrrole (PPy) was doped with polystyrene sulfonate (PSS) to electrochemically deposit a polypyrrole coating on the electrode surface. The film was coated onto the electrode at different thickness, increasing the roughness. The increased roughness (increased effective surface) leads to a decreased overall electrode impedance from about 400 kΩ (bare stent) to less than 10 kΩ (PPy/PSS coating) at 1 kHz. This decrease in impedance leads to improved charge transfer from the electrode to the tissue and an overall more effective electrode for recording and stimulating applications.