Fabrication of High-Aspect-Ratio Microwire Electrodes Using a Vertical Liquid Membrane Electrochemical Etching Method

Abstract

A vertical liquid membrane electrochemical etching method is proposed for the fabrication of high-aspect-ratio microwire electrodes. The potential and current density distributions are simulated using COMSOL software. The simulation results show that the unique potential distribution generated by the proposed method, combined with reciprocating linear motion of the wire electrode, can be used to fabricate microwire electrodes with large aspect ratio. These simulation results are verified experimentally. Different concentrations of electrolyte result in different reaction rates and thus different distributions of the diffusion layer and different bubble flows, resulting in different morphologies of the prepared wire electrodes. The effect of electrolyte concentrations is studied experimentally. At low electrolyte concentrations, the products of electrolysis are removed from the processing area under the action of gravity, and uniform electrodes with high aspect ratio can be prepared. At high electrolyte concentrations, intense bubble production destroys the diffusion layer around the electrode and leads to a dynamic equilibrium state, allowing the preparation of uniform wire electrodes in a rough machining process. The proposed method can prepare wire electrodes with different initial diameters. In this paper, uniform wire electrodes of length 1900 μm, diameter 7 μm, and aspect ratio 270 are fabricated by the proposed method from a tungsten wire of initial diameter 50 μm.