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標題: | 利用水膠膨潤特性開發之微型感測與致動元件 Development of Microsensor and Microactuator Using the Swelling and Shrinking Properties of Hydrogel |
作者: | Jui-Chang Kuo 郭瑞昌 |
指導教授: | 楊燿州(Yao-Joe Yang) |
關鍵字: | 水膠,慣性開關,L-C諧振電路,微機電系統元件,磁場驅動系統,微型手爪, Hydrogel,Inertial switch,L-C resonator,MEMS device,Magnetic driving system,Microgripper, |
出版年 : | 2014 |
學位: | 博士 |
摘要: | 本研究利用水膠材料膨潤特性,設計開發微型感測與致動元件,包含慣性開關與微型手爪。在第一個主題中,我們利用多壁奈米碳管與水膠材料之混合物,發展完全被動式的慣性開關元件。此慣性開關元件結構整合一L-C諧振電路,在玻璃基板上製作出電容電極板與電感線圈,並使用無線的方式感測加速度臨界值。除此之外,慣性開關元件包含一聚二甲基矽氧烷(polydimethylsiloxane, PDMS)的微流道晶片,並且設計有微流道結構,可以填入水膠材料與水滴。當施加於慣性開關之加速度達到設計的臨界值,元件中的水滴便會穿過流道至水膠槽。隨後,水膠吸水膨脹擠壓L-C諧振電路的可變電容,造成電容改變,以及共振頻率變化。共振頻率的變化可以利用無線的方式進行感測。本研究提出之慣性開關不需要任何電源供給,或是裝配任何複雜電路,因此,此元件具有可拋棄性,適合數量大以及低成本的應用。元件的PDMS結構是利用微機電製程的翻模而製作,電極結構則是利用金屬薄膜沉積而定義至玻璃基板上。我們並添加奈米碳管至水膠材料中,以有效縮短慣性開關元件的反應時間。慣性開關的加速度臨界G值,能經由微流道的寬度有效地進行設計。觀察外部線圈的阻抗相位角變化,可以得知慣性開關受到加速度臨界值驅動後,元件的共振頻率會從約164 MHz改變至約148 MHz,達到無線的量測慣性開關的感測結果。
在第二個主題中,我們提出了可以使用磁場無線操控的水膠微型手爪。本研究提出之水膠微型手爪可以自由地在流體中利用直流(direct current, dc)的磁場操控移動,以及利用交流(alternating current, ac)的磁場操控抓取動作。此裝置是利用生物相容性之水膠材料製作而成,適合應用於醫療輔助,如進入人體血管內釋放藥物。經由微影製程,調整不同的紫外光曝光劑量製作水膠材料,可以使水膠材料具有不同的交聯強度,實現水膠微型手爪的抓取動作。本研究提出之微型手爪相關之特性皆完成初步的驗證與探討。量測結果顯示,水膠微型手爪在施加交流磁場,可以使水膠材料內部的奈米磁性顆粒產生加熱的現象,並且在約38oC 時,水膠微型手爪可以達到完整的抓取動作。經由添加多壁奈米碳管至水膠材料中,水膠微型手爪的抓取動作之反應時間可以縮短約兩倍。本研究亦架設了電磁場驅動系統用於操控水膠微型手爪。水膠微型手爪在流體中的操控,如抓取動作、移動之平移與旋轉,已在聚氯乙烯透明管以及PDMS微流道中完成初步的測試。 This work presents the development of micro sensing and actuating devices by adopting the swelling and shrinking properties of hydrogel. The developed devices include an inertial switch and a microgripper. The passive inertial switch employs multiwall carbon nanotube (MWCNT) hydrogel composites integrated with an inductor/capacitor (L-C) resonator. The device consists of a polydimethylsiloxane (PDMS) micro-fluidic chip containing MWCNT-hydrogel composite and water droplet, and a glass substrate with a capacitor plate and an inductor coil. When the acceleration exceeds the designed threshold-level, the water passes through the channel to the hydrogel cavity. The hydrogel swells and changes the capacitance of the integrated L-C resonator, which in turn changes the resonant frequency that can be remotely detected. Each sensor unit does not require on-board power and circuitry for operation, so the proposed device is disposable, and is suitable for low-cost applications. All PDMS structures were fabricated using soft lithography. The L-C resonator was fabricated using a lift-off process to pattern metal layers on a glass substrate. The response time of the device is considerably reduced by introducing MWCNTs into the hydrogel composites. The characterization of the proposed device was also demonstrated. The threshold g-values, which differ for various applications, were strongly affected by the channel widths. The phase-dip measurement shows that the resonant frequencies shift from 164 MHz to approximately 148 MHz when the device is activated by acceleration. Also, we proposed a magnetic hydrogel-based microgripper that can be wirelessly manipulated using magnetic fields. The proposed device can move freely in liquids when driven by direct current (dc) magnetic fields, and perform a gripping motion by using alternating current (ac) magnetic fields. The device is fabricated from a biocompatible hydrogel material that can be employed for intravascular applications. The actuation mechanism for gripping motions is realized by controlling the exposure dose on the hydrogel composite during the lithography process. The preliminary characterization of the device is also presented. The measurement results show that the gripping motion reached a full stroke at approximately 38oC. By dispersing multiwall carbon nanotubes (MWCNT) into the material, the overall response timeof the gripping motion decreases by approximately 2-fold. Device manipulations such as the gripping motion, translational motion, and rotational motion are also successfully demonstrated on a polyvinylchloride (PVC) tube and in a polydimethylsiloxane (PDMS) microfluidic channel. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55469 |
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顯示於系所單位: | 機械工程學系 |
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