The elgiloy microelectrode: Fabrication techniques and characteristics

A glass-insulated microelectrode made from elgiloy orthodontic wire, a stainless cobalt-chromium alloy containing 15% iron, was described by Suzuki and Azuma (1976). Here, we detail a set of modified electrode fabrication procedures, including techniques for hardening and etching the wire, specifying the size, geometry and exposure of the tip, and adjusting tip impedance over a wide range. Accurate insulation of the tip with molten solder glass produces microelectrodes suitable for extracellular recording from single or multiple units and simultaneous recording of evoked potentials. The finished electrode is tough enough to withstand multiple penetrations of the thickened, fibrous dura of the chronic monkey preparation. The iron content allows Prussian blue staining of marking lesions for histological verification of recording sites.