開發光壓電複合材料與其在微流體系統之應用

Development of a Light-activated Optopiezoelectric Thin-Film and its Applications on Microfluidics System

王信互(Hsin-Hu Wang)

指導教授 ： 李世光

共同指導教授 ： 許聿翔(Yu-Hsiang Hsu)

國立臺灣大學/工學院/應用力學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10777

摘要

融合微機電製程技術於機械加工與製程設計，進而運用此類製程技術的高精準度和靈敏度來大幅提升精密加工的精度與成本，已成為近年來機械領域的研究重點之一。舉例而言，透過微機電製程技術來實現複雜機械系統的微小化需求，以開發出種類眾多，包含壓力計、加速計、印表機噴頭、拋棄式醫療用品等在內的低成本高精度致動器或感測器，更為機械製造的發展與應用帶來全新的應用契機。綜觀其優點，包含能減少成本及消耗的樣本及試劑量，能降低人為誤差及分析時間，可有效節省人力成本及提高穩定性等。其中，微型機械致動器諸如微幫浦、微閥門、微混合器等主動元件，因具備優異的致動性能，更具備廣泛應用於國防科技、生物醫學領域、機密製造等重要領域的潛能。
隨著漸增的資源投入微機電系統的應用領域中，微流體與生物分析檢測系統等也日益受矚目。在這微全分析系統(micro total analysis system)中，每一個元件皆需一外接的控制電路或壓力控制管線，才能達到完全自動檢測的功能，也因此整體尺寸無法降低，且整體系統的複雜度極高，因此本研究提出一創新光壓電(Optopiezoelectric)的設計理念，試圖結合光控流體及壓電耦合特性，開發出一光壓電薄膜微幫浦致動元件並應用於微流體系統中。
本研究所提之光壓電機械致動元件，是結合壓電高分子薄膜PVDF (Polyvinylidene Fluoride)與光敏材料酞菁鈦氧TiOPc(Titanium Oxide Phthalocyanine)的特性，以微機電技術(MEMS)製作元件，開發一光壓電薄板微致動器(Optopiezoelectric thin-film actuator)，並透過整合光壓電微幫浦系統驗證致動元件的可行性。有別於以往複雜的外接管路及龐大的驅動來源，本研究只需單一外接電源輸入，便能達到驅動多組主動元件的功能。本研究結合壓電材料的光機電耦合特性，以產生機械形變來推動液體，並結合光敏材料的光導電特性，以提供空間中選擇性驅動的光操控特性，開發了一套低溫光壓電複合薄膜的製程方法。為了能提供最大的形變量，本研究引入有效表面電極及球殼型流道設計，達到最大的液體推動效果。透過選擇性的光罩的設計，使本元件達到時間及空間上可程式化的操控功能。本研究可藉由濃度、厚度及添加摻雜導電物的方式，有效控制光感電極的光電特性及阻抗特性，達到照光前後的阻抗變化(On/Off Ratio值)三個數量極的差異，並透過光感電極的開發與製程，有效提升光壓電薄膜的致動效果。由分析中得知，有效表面電極的半徑佔薄膜半徑的0.7倍有最佳效果，同時新增溝槽亦可提高形變量，且以位置設在電極半徑的0.6倍為最佳。
本研究最終將開發之光壓電薄膜微致動器應用於微幫浦系統進行驗證，並以微機電技術完成流道設計。由實驗驗證單一微幫浦的驅動體積流率為0.652 (μl / min)、雙幫浦驅動的體積流率為1.178 (μl / min)，其體積流率提高約為1.8倍。將週期性照光加入光敏電極驅動光源中，體積流率有效提升至10.116 (μl / min)，為先前光壓電幫浦的8.5倍。驗證並達成了多工性操控(multiple-manipulation)微流體的理念。
本研究實現了光壓電致動器的理念，僅需使用單一的電源輸入，便可實踐動態且多工性的空間及時間的驅動效果，完成具單一驅動多組動態致動之機械介面控制元件，提供了機械領域的關鍵元件與工具，同時也開闢另一個重要的應用舞台，更提供了未來系統應用的成熟、穩定度、以及自由度。

關鍵字

光壓電 ； 壓電致動器 ； 光敏材料 ； 微幫浦 ； 微流體 ； 多功性操控

並列摘要

With the advancement of MEMS technology, sensors and actuators with high accuracy and sensitivity can be massively produced. It plays an important role for the development and application of machinery manufacturing. By combining precise machining technology and complex micro technologies, the price for sensors and actuators are very cost effective. For example, pressure gauges, accelerometers, printer heads, disposable medical supplies, have become major commercialized components in many applications. Further, applications in biomedical devices have drawn attentions from all fields in recent years.
After substantial resources invested from both academia and industries, the MEMS technology has been applied to the applications of microfluidics, biological analysis, clinical diagnosis, environmental analysis, biological studies, and tissue engineering, etc. Its advantages includes low cost, low reagent consumption, minimize human error, and short analyzing time. However, due to the need to integrate a complex operating procedure onto a microchip, multiple active components are needed, such as micropumps, microvalves, and micromixers. Furthermore, each active component still need a power line or a piping system to control each component independently for completing complex operations. Multiple driving source and control units are usually necessary, and the overall device is is still bulky, the operation is complex.
To overcome this limitation, we develop a novel material called “Optopiezoelectric composite.” We combine the advantages of photoconductive polymer and the piezoelectric actuator to develop optopiezoelectric thin-film actuator. Piezoelectric polyvinylidene fluoride (PVDF) provided the mechanical forces to generate bending deformation for pumping. The photoconductive material (titanium oxide phthalocyanine; TiOPc) serves as one of the electrodes of the piezoelectric thin-film that can be spatially and temporally activated by illuminating with a programmable mask and light source.
This study adopted methods such as varying the concentration and thickness as well as mixing conductive materials to effectively control the light-sensitive electrode photoelectric and impedance characteristics. The results achieved demonstrate three orders of difference in impedance change with and without illumination by the light (On/Off ratio). A complete fabrication process was also developed in this thesis. We also use finite element analysis to verify the influence of surface grooves and the effective surface electrode of the optopiezoelectric thin-film, both of which can be used to increase the deformation. The maximum deformation could be as high as 380 µm. When the effective surface of the electrode radius is 0.7 times the entire film was identified to have the best results. The simulation result clearly demonstrated that the level of deformation was a function of groove locations, the number of grooves, and also the side of thin-film that grooves introduced.
By using this technology, only one single external power source is needed to drive multiple active components. Multiple active components could be turned ON and OFF by selectively illuminating light with a programmable mask. To demonstrate the feasibility of this optopiezoelectric composite, we develop a dual micropumping system. A single pump or both pumps can be turned ON and OFF selectively. The volume flow rate for a single micro-pump volume flow rate was 0.652 μl / min, and the volume flow rate increased to 1.178 μl / min with both pumps turned ON. The volume flow rate has increased 1.8 times. We also improve the volume flow rate to 10.116 μl / min with our photoconductive electrode. This experimental result verify the feasibility of optopiezoelectric composite for the capability to operate multiple micropumps with optical manipulations.

並列關鍵字

Optopiezoelectric ； Piezoelectric Actuator ； Photoconductive material ； Micropump ； Microfluidic ； Multiple manipulation

參考文獻

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