Planar reference electrodes on multielectrode arrays for electrochemical measurements of ionic currents

We describe the fabrication process and characterization of polymer coated multielectrode array chips featuring 64 planar Ag/AgCl electrodes for electrophysiological and electrochemical measurements of ionic currents. The multielectrode chip consists of platinum feedlines and microelectrodes fabricated on an oxidized silicon substrate. The feed lines are passivated with a polyimide layer. Silver is deposited electrochemically on the platinum electrodes and chlorinated afterwards resulting in stable micro Ag/AgCl reference electrodes that are recessed within picoliter cavities. We envisage the chip as a platform for high-throughput investigation of lipid bilayers. Schematics of a planar reference electrode. The chips are processed on oxidized silicon (blue) and consist of Pt feedlines (yellow), the Ag/AgCl electrode (black) passivated with polyimide (light blue).