奈米光柵與晶格能隙於電漿子生物感測器之設計與製作

Design and Fabrication of Active Plasmonic Biosensors with Nano-Grating and Band Gap Structures

邱南福(Nan-Fu Chiu)

指導教授 ： 林啟萬

共同指導教授 ： 李君浩(Jiun-Haw Lee)

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.10576

摘要

表面電漿子共振（surface plasmon resonance, SPR）現象，在過去數十年的研究中，此光學感測技術因具有極高的靈敏度、無須螢光標的與可即時分析化驗樣品等優勢，已成功的應用於薄膜的光學特性量測與氣體、化學、生物分子感測。在本論文中，我們藉由探討奈米光柵與晶格能隙在電漿子生物感測之研究，實驗奈米光柵、主動式電漿子與氧化鋅晶格能隙三種電漿子共振耦合之機制，期望達成電激發之整合式電漿子生物感測元件。
實驗中分別利用光激發與電激發方式，在金屬表面上激發有機半導體發光，探討奈米光柵結構與主動式電漿子共振之所產生的電漿子共振與電漿子態隙特性，其優點為不需要外加雷射激發光源及光學極化片，同樣可達到高靈敏度、快速且即時量測之功能。利用電激發有機發光方式，在有機/金屬二層界面上所產生的SPR特性，經由奈米光柵耦合技術，可改變出光的方向性。另外，利用氧化鋅材料的晶格成長特性對表面電漿子共振的影響，我們在單晶及非晶體的氧化鋅中成功量測出表面電漿子共振的差異。
實驗結果方面，我們量測不同的奈米光柵(金屬及非金屬)在電漿子共振效能之差異。並利用金屬奈米光柵進行生化試驗，以不同入射光源量測共振角與待測物折射值之變動比率，在入射光為643nm的變動比率為 與入射光為833nm的變動比率為 。在主動式電漿子實驗結果，我們以有機半導體發光材料當主動層，並進行不同奈米光柵(金，銀，光阻)與調控奈米週期結構，成功量測出主動式電漿子能隙(SP band-gap)間共振效能之差異，在週期的調變下，每改變100nm可調控電漿子耦合動量為 並改變出光角度 的變化，在多層膜的結構下，四層結構的出光效能增強6倍，而半峰全寬(Full Width at Half Maximum, FWHM)小於50nm。我們配合內部本質的表面電漿共振之產生條件，在沿金屬或表面鍍膜的平面上，觀察感測晶片表面因表面生物分子的結合狀況所引起的訊號變動，與不同待測樣品吸收波長不同之原理，進行生醫檢測及化驗。另外在氧化鋅晶格能隙的實驗中，我們探討單晶及非晶體的氧化鋅之間的共振光強反應，實驗出單晶體氧化鋅有極佳的表面電漿共振態。我們比較ZnO/Au與傳統晶片Cr/Au的電漿子共振之差異，ZnO/Au有3倍以上的共振光強反應及小於3倍的半峰全寬(FWHM)，而在禽類病毒(ALV)的實驗中，ZnO/Au也有大於3倍以上的共振光強反應。
預期本技術之產出可同時進行多種表面分子作用之分析，可進一步配合微流道之整合，提供更精確、更微小化的元件設計，使之更適用於高通量與高靈敏度檢測的感測元件之未來發展，更具有製程簡單、成本低、反應速度快、省電、感測體積小等優點，與國內半導體製造技術、光電元件技術與微機電專長相契合具有市場潛力。

關鍵字

表面電漿子共振 ； 奈米光柵 ； 晶格能隙 ； 電漿子生物感測 ； 氧化鋅

並列摘要

Surface plasmon resonance (SPR) phenomenon was described in 1980 and has been used for sensing almost two decades ago. SPR biosensors are optical sensors using polarized surface electromagnetic waves (SEW) to probe molecular interactions between metal film surface and dielectric medium. SPR sensors have the advantages of high sensitivity, label-free and real-time detection. In this paper, the coupling SPP on the nano-grating, the active plasmonics and the zinc oxide (ZnO) band-gap structure for bio-plasmonics were demonstrated. The presented results show that the enhanced performance of plasmonic on nano-grating, the active plasmonics and the ZnO band-gap structure are important for the structure design of novel optical biosensor.
The interaction of SPR on a periodic grating of metal and polymer were investigated in theory and experiment. In addition, we proposed a novel design of plasmonic device without using the conventional external light source and polarizer to produce SPR having the same features, i.e., high sensitivity and real time. The work is based on the electro-excitation of organic and metallic materials, their coupling plasmonics resonance as well as their SP-band gap characteristics. It can induce SPR wave on the metallic surface when proper resonant condition is matched by nano-grating coupled emission. The present experiments provide the multifunctional biological and biochemical sensor technology based on ZnO crystal, which has enhanced sensitivity and accuracy.
We have shown experimentally that strong coupling between electronic and photonic resonances in metal grating and polymer grating really exist. Resonance angle plots of reflectivity of a metal nano-grating sensor, demonstrates the sensitivity of a refractmetric experiment, and . In active plasmonic, our fabricated grating device of various pitches consists of coupled Au, Ag and polymer nanostructure with specific width and symmetric/asymmetric dielectric SP band gap structure. In pitch modulation, results showed that grating at different pitch can match a linear shifting of momentum of about and per 100 nm pitch size. In layer modulation, the resultant emission intensity can achieve a maximum enhancement of 6 times for the 4-Layer device and the Full-Width Half-Maximum (FWHM) was less than 50 nm. We can then observe the emission signal changes due to the presence of surface molecule or specific absorption wavelength of multiple samples. In addition, for ZnO/Au devices tested under water and alcohol, they showed 3 times decrease in FWHM and 3 times the largest shift in intensity interrogation. By testing avian leukosis viruses (ALV) on Cr/Au with ZnO/Au, the ZnO/Au-incorporated chip showed a 3-times enhancement in performance.
In our future work, we will incorporate microfluidics into the device to provide better accuracy and miniaturized design for high throughput applications. We will explore the feasibility of this approach for prototypical systems based on bio-detection or gas-detection. We will miniature optical detectors currently fabricated using VLSI and Optical MEMS integration technology.

並列關鍵字

Surface plasmon resonance ； nano-grating ； band-gap ； bioplasmonics ； zinc oxide (ZnO)

參考文獻

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