以光子晶體生物感測器偵測葡萄糖

Abstract

本篇論文包含兩部份的研究，第一部分是使用氮化鎵發光二極體及二維光子晶體發光二極體作為光源來建構葡萄糖量測系統。第二部分是利用二維光子晶體的繞射機制作為生物感測器來偵測葡萄糖濃度。 近年來物聯網在消費性電子產品中相當熱門，智慧健康照護以及床邊檢測的應用因具有提前預防並遠離疾病的優點，也越來越受重視。生物感測系統結合智慧型手機的研究逐漸蓬勃發展。第一個部分使用兩種光源包含氮化鎵發光二極體以及二維光子晶體發光二極體，製作出一個快速且準確的量測平台來偵測葡萄糖濃度。光的行進方向經過不同折射係數的介質後，產生類似稜鏡的折射，折射光的角度可以對應到葡萄糖濃度的變化。我們量測系統的靈敏度能使每單位折射率產生122°的折射角度變化，且角度與濃度變化呈現很好的線性關係，重複性的測試結果也顯示了量測系統具相當好的穩定性。最後提出了將量測系統結合於智慧型手機的概念，並模擬測試含糖飲料的糖度檢測。 傳統繞射光柵感測器的靈敏度被空間解析度所限制，因此需要較大的空間去改善感測器的解析度。在此篇研究中，我們展示了一個具有高靈敏度、微型量測系統的二維光子晶體生物感測器，光子晶體在空間中將光束衍射到不同的角度，利用位於滿足相位匹配條件與成為消逝波之間的臨界波長來判別施加在感測器表面介質的折射率。使用葡萄糖作為待測物，我們的感測器呈現了相當高的敏感度以及低量測極限，量測系統的靈敏度能使每單位折射率產生3091奈米的波長變化，且最低葡萄糖解析濃度達到0.1mM，結果顯示了我們的生物感測器可以用來偵測臨床糖尿病患者的血糖含量。此部分研究展示了使用二維光子晶體的繞射機制來發展小尺寸的感測器是相當具有潛力的。

This thesis contains two research projects. First, we combined a Gallium Nitride (GaN)-based light-emitting diode (LED) and a photonic crystal (PhC) LED into the detection system to construct a glucose-sensing platform. Second, a PhC biosensor is used to detect glucose concentrations based on the optical diffraction properties from 2-dimensional PhC. Internet of things (IoT) is a popular topic in current consumer electronics. Developing smart health care and the point-of-care testing (POCT) application are also getting more and more attention because of the potential to keep humans away from diseases. Biosensor combined with the smartphone has been a popular research topic. In this part of the research, we show a simple yet accurate detection platform using two kinds of light sources including a GaN-based LED and a PhC LED for glucose-sensing. Radiation profiles with light propagation following a prism-like double diffraction path were characterized. Our system shows a bulk refractometric sensitivity as high as 122.73°/ refractive index unit (RIU) with very good linearity. The repeatability test also shows a nice stability of the system. At last, we proposed a portable detection system model and the glucose content in sugar-sweetened beverages was taken into consideration. Our approach demonstrates the potential of portable glucose detection. The sensitivity of traditional diffraction grating sensors is limited by the spatial resolution. Thus a large space is required in order to improve sensor performance. In this part of the research, we demonstrate a hexagonal PhC biosensor with high sensitivity and a compact measurement range. The PhCs are able to diffract optical beams to various angles in the azimuthal space. The critical wavelength that satisfies the phase matching or becomes evanescent is employed to benchmark the refractive index of the material applied to the sensor. Using glucose solution as the analyte, our sensor demonstrates very high sensitivity and low limits of detection (LOD). The sensitivity of our measurement system is calculated to be 3091 nm/RIU and the LOD is 0.1mM. The result shows our sensor is capable of detecting clinical cut-off blood sugar for Diabetes patients. It shows the diffraction mechanism from the hexagonal PhCs can be used for sensors when the compact size is a concern.