UV-LIGA technique for ECF micropumps using back UV exposure and self-alignment
UV-LIGA technique for ECF micropumps using back UV exposure and self-alignment
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DOI：
10.1088/1361-6439/aa8d9a
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发表时间：
2017-10
影响因子：
2.3
通讯作者：
Dong Han;Y. Xia;Shinichi Yokota;Joon-wan Kim
中科院分区：
文献类型：
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作者：
Dong Han;Y. Xia;Shinichi Yokota;Joon-wan Kim
本文提出并开发了一种新型 UV-LIGA 技术，利用背紫外曝光和自对准来实现高功率密度电共轭流体 (ECF) 微泵中的高深宽比微加工 (HARM)。 ECF是一种功能流体，设计用于在施加高直流电压时能够在ECF的阳极和阴极之间产生强烈且活跃的射流（ECF喷射）。我们开发了由 HARM 制造的三角棱柱和狭缝电极对 (TPSE) 组成的高功率密度 ECF 微型泵。传统的HARM UV-LIGA技术主要分为两种方法：（a）单厚层和（b）多个薄层。这两种方法都有局限性——前者会使模具变形，而后者会导致层之间错位。使用有限元方法软件 COMSOL Multiphysics，我们证明变形的微型模具会严重损害 ECF 微型泵的性能。此外，我们通过实验证明，错位很容易引发ECF微型泵的放电。为了克服这些限制，我们构思了一种新概念，利用电铸种子电极层作为紫外线屏蔽层，并通过背面紫外线曝光形成图案光致抗蚀剂（KMPR）。种子电极层应由用于图案化的不透明导体（Au/Ti）和用于布线的透明导体（ITO）组成。我们提出了由细金属线图案组成的类似透明电极的概念，而不是 ITO。为了验证这一概念，对厚度为 70、220 和 500 µm 的 KMPR 层进行了实验研究。在500 µm KMPR厚度的情况下，类透明电极的概念得到了部分证明。结果，成功制造了高度为 440 µm 的 TPSE。特性实验表明，背紫外制造的ECF微泵（367 mW cm−3）与前紫外制造的ECF微泵（391 mW cm−3）几乎具有相同的输出功率密度。本文证明，所提出的 UV-LIGA 技术利用背紫外曝光和自对准，可以有效地制造具有高输出功率密度的 ECF 微型泵的 TPSE。
This paper proposes and develops a novel UV-LIGA technique using back UV exposure and self-alignment to realize high aspect ratio micromachining (HARM) in high power density electro-conjugate fluid (ECF) micropumps. ECF is a functional fluid designed to be able to generate strong and active jet flow (ECF jetting) between anode and cathode in ECF when high DC voltage is applied. We have developed high power density ECF micropumps consisting of triangular prism and slit electrode pairs (TPSEs) fabricated by HARM. The traditional UV-LIGA technique for HARM is mainly divided into two approaches: (a) single thick layer and (b) multiple thin layers. Both methods have limitations—deformed molds in the former and misalignment between layers in the latter. Using the finite element method software COMSOL Multiphysics, we demonstrate that the deformed micro-molds critically impair the performance of ECF micropumps. In addition, we experimentally prove that the misalignment would easily trigger electric discharge in the ECF micropumps. To overcome these limitations, we conceive a new concept utilizing the seed electrode layer for electroforming as the UV shield and pattern photoresist (KMPR) by back UV exposure. The seed electrode layer should be composed of a non-transparent conductor (Au/Ti) for patterning and a transparent conductor (ITO) for wiring. Instead of ITO, we propose the concept of transparency-like electrodes comprised of thin metal line patterns. To verify this concept, KMPR layers with thicknesses of 70, 220, and 500 µm are experimentally investigated. In the case of 500 µm KMPR thickness, the concept of transparency-like electrode was partially proved. As a result, TPSEs with a height of 440 µm were successfully fabricated. Characteristic experiments demonstrated that ECF micropumps (367 mW cm−3) fabricated by back UV achieved almost the same output power density as ECF micropumps (391 mW cm−3) fabricated by front UV. This paper proves that the proposed UV-LIGA technique, using back UV exposure and self-alignment, can effectively fabricate TPSEs for ECF micropumps with high output power density.