Optics and Precision Engineering, Volume. 32, Issue 16, 2492(2024)
Preparation of Ni microneedle array using thin photoresist microelectroforming technique
With the advantages of high mechanical strength and good electrical conductivity, Ni microneedle arrays are widely used in bioengineering and other fields. By virtue of the advantages of high replication accuracy and wide adaptability, the microelectroforming technique has become a reliable method for preparing Ni microneedles. However, it is usually necessary to use photoresist template with the same thickness as that of the casting layer in the microelectroforming technique. Thick photoresist microelectroforming faces problems such as residual photoresist at the microstructure, difficulty in removing the photoresist. In order to solve the above problems, obtain Ni microneedle arrays with tip curvature radius on the nanometer scale, the fabrication process for Ni microneedle arrays based on the thin photoresist microelectroforming technique was designed and experimentally verified. First, a silicon template with arrays of pits was fabricated on (100) single crystal silicon wafers. Next, a Ni seed layer with a thickness of 200 nm was sputtered onto the surface of the silicon template. Then, a thin photoresist template of the microneedle support beam was prepared using the photolithography technique. Finally, Ni microneedle arrays were released after microelectroforming. The experimental results show that Ni microneedle arrays with an average deviation in size of 1.7 μm, an average deviation in absolute position of 1.8 μm, and an average curvature radius of 150 nm at the tip were obtained by this method without damaging the silicon template. Using RFJ-60 negative photoresist as a template for microelectroforming with a thickness of -2 μm, microneedle support beams with a thickness of -24.3 μm were successfully prepared. Ni microneedle relative dimensional error was reduced to 1% by compensating SiO2 lateral erosion into lithographic mask. Combining the microelectroforming technique and the anisotropic etching property of monocrystalline silicon, the Ni microneedle array can be prepared with high quality and high efficiency, which lays the foundation for the batch preparation of Ni microneedle arrays.
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Huaan WANG, Xiaojian LI, Penghe YIN, Jiaxin SONG, Yu ZHANG, Junsheng LIANG. Preparation of Ni microneedle array using thin photoresist microelectroforming technique[J]. Optics and Precision Engineering, 2024, 32(16): 2492
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Received: Feb. 5, 2024
Accepted: --
Published Online: Nov. 18, 2024
The Author Email: Junsheng LIANG (jsliang@dlut.edu.cn)