Electrochemical polishing of microfluidic moulds made of tungsten using a bi-layer electrolyte

Abstract

Microfluidic chips made of glass are important analytical devices for applications in biomedicine, drug development and chemical analysis. For the mass production of glass-based microfluidic chips, tungsten-made microfluidic moulds are indispensable. In this paper, a dynamic electrochemical polishing (ECP) process using a bi-layer NaOH electrolyte is proposed to uniformly polish tungsten moulds. The ECP conditions are optimized to determine the best anode potential and polishing duration. The problem of pitting during ECP can be solved by an ultra-short ECP post-treatment of several seconds. During static ECP, the material removal on the mould is nonuniform, and material removal uniformity is greatly improved by dynamic ECP. After 10 cycles of dynamic ECP, a tungsten mould with a mirror surface is obtained, and the surface roughness (Sa) is drastically reduced from 205.98 nm to 4.14 nm. The results presented in this paper demonstrate that dynamic ECP is a promising approach for highly efficient and uniform polishing of tungsten moulds with microscopic features.