應用高深寬比微影於尼龍濾膜基材之製程與微型元件之開發

A High-Aspect-Ratio Process with Nylon Membrane Filters for Fabricating Miniaturized Devices

馬政文(Cheng-Wen Ma)

指導教授 ： 楊燿州

國立臺灣大學/工學院/機械工程學研究所/博士(2016年)

https://doi.org/10.6342/NTU201600942

摘要

本研究運用高深寬比SU-8光阻微影製程於尼龍濾膜之技術，並實現研製多種微型元件，包括剪力感測陣列、超級電容、與高靈敏度觸覺感測陣列。在第一個主題中，我們開發一種創新的2 × 2剪力感測陣列。利用簡單的真空過濾技術，配合所製作的SU-8微影結構之模具，將巴克紙圖形化於可撓的尼龍濾膜上。用此當作觸覺感測器的感測單元，並將其封裝於彈性的聚二甲基矽氧烷結構中。所製作出的高深寬比感測單元具有壓阻效應的感測機制，此外，利用此方式製作的感測器具有多項優點，例如：異向性感測能力(Anisotropic sensing capability)、可撓性、製程簡單與低成本。論文中完成壓/剪力的量測架設。探討了施加正向力與剪力於感測陣列上所造成的電阻變化情形。此外，也利用所開發之掃描電路將所受到的壓/剪力量分佈透過所開發的程式顯示於電腦螢幕。
在第二個主題中，利用真空過濾技術，配合開發之SU-8微影結構。在尼龍濾膜上將巴克紙圖形化為指叉的形狀，作為超級電容器的電極，並將其封裝於固態電解液(PVA-KOH)中。此方式的好處是可以輕易地增加電極的深寬比，因此可有效地增加超級電容的比電容值。而因為基底為可撓的尼龍濾膜，整體元件具有可撓的特性。因此具有裝置在可撓式電子裝置中的潛力。此研究也利用多種的電化學分析技術探討超級電容的特性。利用循環伏安法，在20 mV/s掃描速率下，可量測到的最大比電容值107.27 mF/cm2。且以掃描速率為1 V/s的條件下經過1000次的充放電循環後，電容值保有率高達96.59%，顯示本研究之超級電容具有良好的電容穩定性。元件的漏電流量測結果顯示此元件漏電流僅9.95 μA，顯示所儲存之電能維持更久的時間。透過恆電流充放電量測實驗也顯示此元件具有良好的充放電效果。而此研究也透過交流阻抗量測分析超級電容各部件的特性。
在第三個主題中，研究製作了創新的8 × 8高靈敏度觸覺感測陣列。陣列中的感測單元的材料為由聚二甲基矽氧烷(PDMS)與多壁奈米碳管混合而成的導電高分子。尼龍濾膜被用來當作製作SU-8模具的基材，而導電高分子的微結構則是經由濾膜的孔洞翻模而來。論文中也證實了感測器的靈敏度提升的方式是由導電高分子微結構互相接觸所產生的穿隧壓阻效應而來。另外，也比較了不同孔徑濾紙翻製的結構其靈敏度的不同。量測的架設也在論文中提及。元件量測到的最大靈敏度為-7.73 kPa-1，反應時間為4 ms。其感測陣列均勻性、重複性、干擾和遲滯效應也在文章中提及。最後也將感測器應用在偵測蜜蜂行走的軌跡和人類手肘運的所產生的壓力變化。

關鍵字

奈米碳管 ； 巴克紙 ； 觸覺感測器 ； 超級電容 ； 真空過濾 ； 尼龍濾膜 ； 導電高分子

並列摘要

This work proposed a novel lithography process for fabricating a patterned SU-8 mold on a nylon membrane filter. The proposed technique is employed to realize various miniaturized devices, including a flexible tactile and shear sensing array, a supercapacitor, and a highly sensitive tactile sensing array. A flexible tactile and shear sensing array incorporating patterned buckypaper as the sensing elements and presents a novel process for patterning buckypaper at a high aspect ratio. The fabricated sensing device features advantages such as an anisotropic sensing capability, flexibility, ease of fabrication, and a low cost. Analyzing the measured resistance versus applied shear force on a single sensing element revealed that the sensitivity of the element varied along different directions. This anisotropic sensing capability can be employed to improve shear sensing. In addition, the sensing elements exhibited favorable sensitivity and repeatability. Force images were obtained using a 2 × 2 shear-force sensing array when various normal and shear forces were applied.
We further proposed a paper-like micro-supercapacitor with in-plane interdigital buckypaper electrodes on a filter membrane substrate in this thesis. A vacuum filtration method assisted by lithography techniques was proposed for patterning the buckypaper. The benefits of the proposed micro-SC include a flexible structure, simple fabrication, easy chip integration, and high specific capacitance. By increasing the aspect ratio of the patterned buckypaper electrodes, the specific capacitance of the micro-SC was effectively enhanced. The specific capacitance measured using cyclic voltammetry was 107.27 mF/cm2 at a scan rate of 20 mV/s. The measured charge–discharge behaviors at various discharge rates revealed the electrochemical stability of the device. The measured leakage current was approximately 9.95 µA after 3600 s. The device exhibited high cycle stability with 96.59% specific capacitance retention after 1000 cycles.
Also, we proposed a highly sensitive tactile sensing array. Sensing elements of the array comprise multiwall carbon nanotubes and polydimethylsiloxane polymer. A novel lithography process is proposed for fabricating an SU-8 mold for shaping the sensing cells in the array. In addition, a nylon membrane filter is proposed to serve as a mold for numerous microdome patterns, which were transferred onto a conductive polymer film. The proposed device features advantages, such as ultra-high sensitivity, flexibility, and a simple fabrication process. Tunneling piezoresistive effects of interlocked microdome structures fabricated using membrane filters with different pore sizes were observed. The measured maximum sensitivity and typical response time were approximately −7.73 kPa−1 and 4 ms, respectively. In addition, the measured results show that the patterned polymer composite arranged in a row–column array can effectively eliminate the crosstalk effect. Moreover, measurements for various tactile sensing applications were demonstrated.

並列關鍵字

Carbon nanotube ； Buckypaper ； Tactile sensor ； Supercapacitor ； Vacuum filtration ； Nylon membrane filter ； Conductive polymer

參考文獻

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