在這篇論文中，我們設計一個以隙環共振器為主的超材料吸收體，希冀能夠達成同時具有折射率感測以及表面增強紅外光吸收檢測效應的雙功能感測器功能。在折射率感測部分中，我們利用超材料吸收體的共振頻率會隨著環境折射率的變化而偏移的特性，來監測環境的折射率。由於我們的目標工作頻率為中紅外區域，其具有較強烈的水吸收峰值，所以我們選擇不同厚度的聚甲基丙烯酸甲酯（PMMA）作為待測物，並由Maxwell Garnett方程式計算出在不同厚度情況下對應的折射率。在模擬中，該超材料吸收體的檢測靈敏度可高達到1602.5 nm/RIU。而在實驗部分，量測出的檢測靈敏度亦接近993.8 nm/RIU，與模擬結果極為接近。另一方面，我們亦檢測了超材料吸收體在表面增強紅外光吸收檢測的能力。此處，吸收體的共振模式會與位於相同頻率待測物的分子振動模式重疊，並產生“法諾共振”（Fano resonance），此共振模式會造成特徵頻譜的形狀反轉，使得我們更易於判斷待測物存在的與否。作為紅外光吸收檢測的目標分析物，我們選擇聚氯乙烯(PVC)，這是一種在眾多行業中廣泛使用的常見聚合物。我們在模擬和實驗中確認了法諾共振的存在，且其檢測極限可以達到0.5％，成功地定性超材料吸收體在紅外光吸收檢測的表現。然而，受到低濃度PVC薄膜在超材料吸收體分佈不均的阻礙，我們未能定量分析表面增強紅外光吸收信號和PVC濃度的關係。總結以上研究成果，我們成功地提出了一個具有折射率感測以及表面增強紅外光吸收特性之雙功能超材料吸收體感測器，在實驗中其折射率感測靈敏度可接近1000 nm/RIU。然而，其缺乏用於表面增強紅外光吸收來定量檢測PVC的濃度。

In this dissertation, we develop a split-ring resonator based metamaterial absorber (MA) to achieve a bifunctional sensor of refractive index and surface enhanced infrared absorption sensing. For the design of a refractive index sensor, we use the property that the operating frequency of the MA would shift according to environmental refraction index to detect the index change of environments. Here, our target frequency is located at mid-infrared regime, which reveals strong water absorption at this regime, so we choose polymethyl methacrylate (PMMA) with different thicknesses as our analytes to testify the behavior of our proposed MA. Note that the corresponding refractive indices of PMMA with different thicknesses are calculated via Maxwell-Garnett formula. The simulated and experimentally measured sensitivities are up to 1602.5 nm/RIU and 993.8 nm/RIU, respectively, suggesting the good agreement between the simulation and measurement. On the other hand, we also characterize the properties of surface enhanced infrared absorption (SEIRA) from our proposed MA. In SEIRA, the operating frequency of the MA should be tuned to coincide with a vibrational mode of our targeted analytes to show ‘Fano resonance’ with inverted optical responses compared to absorption spectra of the MA only, facilitating the determination of the existence of the analytes. It is worth mentioning that the targeted analytes here is PVC, a commonly used polymer in every industrial field. We confirm the Fano resonance in the simulation and measurement with a detection limit down to 0.5%, qualitatively demonstrating the behavior of our MA in SEIRA detection. Yet, due to non-uniform distribution of PMMA on our MA, we cannot quantitatively draw a relationship between the concentration of PVC and measured SEIRA signals. In summary, we successfully proposed a bifunctional sensor with refractive index and surface enhanced infrared absorption sensing. The sensitivity of refractive index sensing could up to 1000 nm/RIU while the MA indeed reveals Fano resonance with the applied PVC. Still, the measured MA could not quantitatively distinguish the concentration of PVC when it is low.

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