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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. [ABSTRACT FROM AUTHOR]

The curved Fresnel lens array on the spherical surface owns exceptional optical performance and meets the growing demand for smart home and security alarm systems. However, the intricate three-dimensional microstructure of such optical component is typically considered impossible to be directly fabricated by diamond machining. In this paper, a novel 6-axis diamond ruling method is proposed to fabricate the complex optics utilizing a commercial 6-axis ultra-precision machine tool. The kinematic principle and tool path generation algorithm of this method are presented. A varying-angle sampling strategy is employed in the proposed algorithm to reduce the acceleration and following error in the rotation of the A-axis. Novel trial cutting processes are introduced to figure out the tool setting errors induced by visual inspection, which need to be compensated in the tool path. Based on the proposed tool path generation algorithm and cutting processes, this method enables the efficient processing of precise curved Fresnel lenses. There is no interference between the diamond tool and the curved microstructure in the 6-axis synchronized motions. Finally, the feasibility and superiority of this method are experimentally verified by analyzing the surface roughness and shape accuracy of the machined component. It can indeed generate high-quality curved Fresnel lenses on the spherical surface by the proposed 6-axis diamond ruling method. • A 6-axis diamond ruling method is proposed to fabricate the curved Fresnel lens array on the spherical surface. • The nonlinear kinematic principle of the method is presented. • The tool setting errors are eliminated by the novel trial cutting processes. • A vary-angle sampling strategy is employed to disperse the spatial Archimedean spiral. • The tool path generation algorithm for the 6-axis diamond ruling is introduced and validated. [ABSTRACT FROM AUTHOR]