Low-impedance thin-film polycrystalline silicon microelectrodes for extracellular stimulation and recording

Polycrystalline silicon thin films were explored with respect to their appl ication as low-impedance microelectrodes for extracellular stimulation and recording of cells. Microelectrode arrays (MEAs) comprising polysilicon mic roelectrodes were fabricated using CMOS-compatible processes. Overall capac itance of an electrode with a diameter of 20 mu m is on the order of 200-30 0 pF. Chemical and morphological stability in physiological saline solution was excellent over a period of at least 5 months. This finding renders app lications in neuronal implants or bio-chips. Nanoporous polysilicon electro des were created by anodic oxidation in hydrofluoric acid (HF). However, no considerable decrease of electrode impedance was observed although pore fo rmation was clearly confirmed by transmission electron microscopy (TEM). (C ) 1999 Elsevier Science S.A. All rights reserved.