Combining Pedot:Pss Polymer Coating with Metallic 3d Nanowires Electrodes to Achieve High Electrochemical Performances for Neuronal Interfacing Applications.

Electrophysiology studies facilitate the understanding of mechanisms involved in neuronal networks. Latest advances consist of integrating 3D-nanostructures to microelectrodes arrays technologies to increase the electrodes surface-to-volume ratio, which leads to a higher affinity with cells, enables subcellular interactions and high neuronal signal resolution. However, due to their small effective area, such devices suffer from their high interface impedance and limited charge transfer capacity. These performances can be improved by optimizing the properties of the interface material at the nanoscale. Conductive polymer coatings are ideal candidates to overcome these limitations, as they are biocompatible, have the potential to reduce the mechanical mismatch at the electrode/cell interface and possess remarkable electrochemical performances. Here, we propose to combine metallic 3D nanowires-based electrodes (NWs), made of platinum silicide, whose design encourage optimal cell engulfment, with the remarkable properties of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) coating. We demonstrate, for the first time, the ability to deposit with a very high selectivity, ultra-thin layers of conductive polymer (<50 nm) onto metallic electrodes using electrodeposition. We first studied the impact of the PEDOT:PSS coating on planar electrodes of diameters down to 5 μm, used for surface scaling investigation, then on high aspect ratio vertical nanostructures. These polymer-coated electrodes have been fully characterized, both electrochemically and morphologically, in order to establish a direct relationship between the synthesis conditions, the morphology and the conductive features. Results show that PEDOT-coated electrodes exhibit drastic thickness-dependent improved stimulation and recording performances, which offers new perspectives for neuronal interfacing with optimal cell engulfment. This should enable the study of neuronal activity with acute spatial and signal resolution at the sub-cellular level. This article is protected by copyright. All rights reserved.