Stainless Steel Micro-Needle Electrodes Made by Electrolytic Pointing

Abstract

Micro‐needle electrodes of any desired taper and sharpness for insertion into living tissue can be made quickly by electrolytic etching. For stainless steel wire the electrolyte is a mixture of sulfuric and ortho‐phosphoric acids. The wire to be pointed is made the anode of a circuit initially carrying about 0.03 amp. Gross shaping of the needle is done by repeatedly immersing the wire and withdrawing it slowly from the bath. Fine shaping of the point is carried out with reduced current. The electrodes are finished by insulating all but the fine tip with a baking enamel. The process described is adaptable to making a batch of micro‐needles at one time.