Soft-lithographic methods for the fabrication of dielectrophoretic devices using molds by proton beam writing 指導教授：許藝菊 報告者：陳亞維

 Introduction  Experiments  Results and discussion  Conclusions

 Soft-lithographic ：透過多次翻模、轉移之技術來製 造出微米以及奈米的結構  PBW ：利用 MeV 能量的聚焦​​質子束對材料直接刻寫 微奈米尺度微結構  Replica molding ：利用 PDMS 灌注在母模上，待固化 後即可得到與母模相對應結構 Keywords

 SU-8 ：負光阻，化學、熱穩定性高，高穿透性， 以及有良好的結構體之厚度以及深寬比  Poly-dimethylsiloxane (PDMS) ： 為目前生醫微機電系統 (Bio-MEMS) 常使用的材料 低溫下依然具有柔軟、彈性與可塑性

 In this paper, soft-lithographic methods for the fabrication of 3D-DEP devices equipped with high- aspect-ratio pillars,  combined with a PDMS micro-fluidic channel replicated from a SU-8 mold fabricated by PBW Introduction

Experiments PBW of SU-8 layer on silica for patterning pillar arrays and a mold for a micro-fluidic channel

Soft ithography of micro-fluidic channel by the SU-8 mold

Sealing the pillar arrays on silica with the PDMS, where the silica substrate with pillar arrays is bonded to PDMS with a micro-fluidic channel

Results and discussion Fig. 3a shows a SEM image of the part of pillar arrays with an area of 1.0 mm 80 µ m by PBW onto a 15 µ m thick SU- 8 on a silica substrate High-aspect-ratio pillars (rectangular of 2.5x6.8 µ m in shape and 13 µ m in height) were observed with smooth and vertical surface, as shown in Fig. 3b.

 Fig. 4a shows the SEM image of a SU-8 mold with 200 µ m in width and 2.0 mm in length and 20 µ m in height.  Following the process illustrated in Fig. 1b, the pattern of the SU-8 mold was successfully transferred to PDMS, as shown in Fig. 4b.

 From an optical microscope image in Fig. 5a  Fig. 5b shows a photograph of the DEP device with tubing at inlet and outlet ports.  Thanks to the plasma treatment, the tight sealing was achieved and no leakage was observed.

 Fig. 6a shows a SEM image of a SU-8 mold with arrays of holes with rectangle of 7.0 X 5.3 µm^ 2 in shape and 12 µm in depth.  As shown in Fig. 6b, the holes were successfully replicated to PDMS as arrays of pillars.

 important to lower the adhesion force between the SU-8 mold and PDMS and alignment of vertical direction during separation to avoid fracture of PDMS replica,

Conclusions  A soft lithography technique combined with PBW was successfully applied to the fabrication of the 3D-DEP device equipped with high- aspect-ratio pillar arrays in micro-fluidic channel.

 The most critical part of the process is pattern transfer of the high-aspect pillar from the SU-8 mold to PDMS. Replication of relatively low-aspect-ratio pillar arrays was successful.  Trials of successful replication of both pillar arrays and a micro-fluidic channel are underway for DEP devices with more complex structures.

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