A rapid method for production of sharp tips on preinsulated microwires.

A rapid method is described which makes it possible to obtain sharp, pencil-like tips on factory-insulated tungsten wires. These features cannot be achieved on preinsulated wire using electrolytic etching techniques. In essence, the cut end of an insulated 25 micron wire is ground on a flat metal surface containing a thin layer of powdered diamond. When both the wire and the diamond-covered disc are rotated simultaneously, a sharp pointed tip is produced within 2-5 min with a smoothly tapering sleeve of insulation. The resulting tips yielded high-quality single-unit spike trains when tested in rat cochlear nucleus. This method lends itself well to those single unit or multineuronal studies requiring rapid, low-cost electrode production, and minimum tissue damage.