3D passive microfluidic valves in silicon and glass using grayscale lithography and reactive ion etching transfer

作者：Hai Binh Phi, Sebastian Böhm, Erich Runge, Lars Dittrich, Steffen Strehle · 发表于：Microfluidics and Nanofluidics · 年份：2023 · DOI：10.1007/s10404-023-02663-2 · 被引用次数：16 · 研究领域：Microfluidic and Capillary Electrophoresis Applications、Innovative Microfluidic and Catalytic Techniques Innovation、Microfluidic and Bio-sensing Technologies

Abstract A fabrication strategy for high-efficiency passive three-dimensional microfluidic valves with no mechanical parts fabricated in silicon and glass substrates is presented. 3D diffuser-nozzle valve structures were produced and characterized in their added value in comparison to conventional diffuser-nozzle valve designs with rectangular cross sections. A grayscale lithography approach for 3D photoresist structuring combined with a proportional transfer by reactive ion etching allowed to transfer 3D resist valve designs with high precision into the targeted substrate material. The efficiency with respect to the rectification characteristics or so-called diodicity of the studied valve designs is defined as the ratio of the pressure drops in backward and forward flow directions. The studied valve designs were characterized experimentally as well as numerically based on finite element simulations with overall matching results that demonstrate a significantly improved flow rectification of the 3D valves compared to the corresponding conventional structure. Our novel 3D valve structures show, for instance, even without systematic optimization a measured diodicity of up to 1.5 at low flow rates of only about 10 μl/s.