A PENETRATING MULTI-ELECTRODE RECORDING ARRAY SUITABLE FOR TOP INSERTION OR DISH BOTTOM

We have developed a new microelectrode array system for recording multi-unit activity in retina or brain slices.  The array consists of planar assemblies of 4-10 microelectrodes less than 100 micrometers thick that can be stacked to produce a sandwich of up to 100 microelectrodes. One stack configuration has lead wires exiting the stack at a 45-degree angle suitable for mounting on a micromanipulator for insertion into the tissue from above. A second configuration has lead wires exiting the stack at right angles, suitable for dish bottom mounting. The individual microelectrodes are spark-etched stainless steel or tungsten wires, typically 25 micrometers in diameter. We have made stable recordings with the top penetration version of the array for more than 6 hours from rabbit retinal ganglion cells in an isolated eyecup preparation.  These arrays have been used them repeatedly for months without degradation in recording quality, provided that tissue debris is removed after each use.