低成本可撓式常壓微電漿裝置設計及其於無光罩表面圖案化之應用

Abstract

常壓微電漿系統因不需要真空系統，且電子密度和能量密度高，能在局部區 域提供高反應性，在近年來有許多相關的製程與研究被報導。本研究提出三種低 成本、且可撓式微電漿裝置系統：紙基直流電源驅動薄膜平行式電極型電漿裝置、 紙基介電質放電型微電漿裝置、以及以印刷電路板為基底之微電漿產生裝置。本 研究所提出的紙基微電漿裝置，為世界上第一個製作在紙基材上的微電漿系統。 紙基直流電源驅動薄膜平行式電極型電漿裝置是以網版印刷的方式將導電碳 膠塗佈在紙基材上做為電極之用。此種電漿裝置依操作條件不同可觀察到「自我 脈衝模式」與「穩定模式」兩種放電表現，且在高施加電壓下容易形成穩定模式。 兩種放電模式的成因可以系統負載線與電漿非線性特徵曲線的關係說明。此裝置 可應用於元素之定性分析。實驗時將鹽類水溶液滴在兩電極間隙後，使水分蒸乾 讓鹽類顆粒落在電極間隙，並施加一高電壓使電漿生成。透過比對所量測之電漿 放射光譜與資料庫中元素之特徵放光波長，可檢測待測物中之元素，且實驗結果 顯示可偵測到ng等級的金屬。 上述電漿裝置因物理上的限制，電漿僅能夠在局部區域生成，無法產生大面 積的電漿放電，因而限制了電漿的應用性。為改善此問題，本研究改變電極配置 方式，提出紙基介電質放電型微電漿裝置。此裝置可在Ar、He、和空氣的氣氛下 操作，且可同時在多個微腔體內生成低溫電漿。因紙基板可撓曲之特性，電漿裝 置可在非平面的狀態下操作。實驗利用紙張具有毛細力的特性，將液相先驅物儲 存於電極的紙張上，利用無光罩製程在玻璃基板上製作具有抗蛋白質吸附特性的 類聚氧化乙烯圖案。 第三種裝置是以印刷電路板為基底之微電漿產生裝置。電極上的圖案利用「印 表機碳粉轉印技術」製作，製程不需使用無塵室之設備。實驗利用此裝置可撓曲 之特性，透過沉積疏水的氟碳高分子或移除材料表面的疏水薄膜的方式在平面與 非平面製作親疏水對比圖案。若同時在雙面印刷電路板的兩面製作圖案，使電漿 能同時在兩面生成，則裝置可同時對兩個表面進行表面圖案化製程。實驗中以此 電漿裝置製備表面張力侷限微流道裝置。 本研究所提出之微電漿裝置在兩方面上具有彈性：第一，所使用的基板為可 撓性的紙張或印刷電路板，故裝置可在非平面下操作。第二，裝置的製作過程不 需使用無塵室的設備即可完成，因此使用者隨時可依自己的需求製作圖案，且從 圖案設計完到完成電漿裝置僅需半個小時，增加微電漿使用上的彈性。

A lot of efforts have been made on atmospheric microplasma systems since such type of plasma systems does not need vacuum systems, and has unique properties such as high electron density, high power density, and being able to create highly reactive environment in a local area. In this thesis, three types of cost-effective and flexible microplasma systems are reported: direct-current-driven paper-based coplanar microplasma device, paper-based dielectric-barrier-discharge-type microplasma array device, and printed-circuit-boared-based microplasma generation device. This work presents the first microplasma system fabricated on paper substrates. The direct-current-driven paper-based coplanar microplasma device is made by coating conductive carbon paste on paper substrates with screen printing method. Such type of devices has two types of discharge behaviors, namely, self-pulsing mode and stable mode, and the system can easily move into stable mode at high applied voltages. The mechanism of the two different discharge behaviors can be understood by looking into the load line of the system and the non-linear IV behavior of plasmas. By adding a drop of salt solution into the gap between the electrodes and acquiring the emission emanating from the plasma, we can detect the metallic elements with the optical emission spectra. The experimental results show that the detecting limit can be as low as nanogram. Because of the limitation of dc-driven plasmas, the plasma can only be ignited in a small area which limits the application of plasmas. We therefore design a paper-based dielectric-barrier-discharge-type microplasma array device. The device can operate in different atmospheres such as Ar, He, and air, and have discharges in every microcavity. Due to the fact that paper is a flexible substrate, the proposed device is able to generate plasmas even when the substrate is not flat. By utilizing the capillary force of paper substrates, we stored the liquid precursor in the fibers of paper, and create polyethylene-oxide-like patterns with the protein-repelling property on a glass substrate. The third type of microplasma generation devices is made of double-sided printed circuit board. The patterns on the copper electrode are fabricated by “toner-transfer method” without the need of clean room facilities. By taking the advantage of the flexibility of the device, we can create hydrophobic/hydrophilic contrast on flat and non-flat surfaces by depositing fluorocaronbon polymers or removing hydrophobic films. The device is able to pattern two surfaces simultaneously with patterned double-side printed circuit board on two sides. This technique was applied to fabricate surface-tension-confined mirofluidic devices. The microplasma devices proposed in this thesis are flexible in two ways: first, the substrates used here are flexible, and therefore the devices can be operated under non-flat conditions. Secondly, the electrode-patterning process does not need clean room facilities, and the users can design their own patterns anytime. The device fabrication process takes less than 30 min.