PEDOT:PSS coated Gold Nanopillar Microelectrodes with Ultralow Impedance for Neural Interfaces

Improving the neuron-electrode interface has been a focus of biomedical research for the last decade. Low impedance, high charge storage capacities and small geometrical surface area are desired for excellent recording conditions. A common way to improve this interface is to increase the electrochemically active surface area of the electrode using nanoporous or nanostructured electrode materials. In this paper, the fabrication of microelectrodes with very high aspect ratio gold nanopillars coated with the conducting polymer PEDOT:PSS is presented. The electrodes are simulated, manufactured and studied using scanning electron microscopy, atomic force microscopy, impedance spectroscopy, cyclic voltammetry and neural cell culture experiments. We show that PEDOT:PSS coated nanopillar electrodes have improved capacity, reduced impedance and in-vitro recordings reveal high signal-to-noise ratio. Depending on pillar height the impedance is more than 350 times smaller compared to planar gold electrodes at 1 kHz and reveals an electrode capacity more than 1,000 times higher.