利用矽基光子晶體感測器分析葡萄糖濃度

Abstract

近年來，物聯網逐漸興起，穿戴式裝置及各式建置物聯網所需的感測器需求使的這個領域具有龐大的市場需求。物聯網應用於生物感測器上如食品安全、醫學檢測、藥品測試上，能夠以低成本、高性價比製作而成的感測器相當吸引人。生物感測器如二維光子晶體生物感測器，其量測極限已能到達相當低的物質濃度。唯其使用之量測設備諸如光源及偵測器之價格仍相當高昂，使用低解析度及低成本光源又能維持相當的量測精度為普及生物感測器之重要課題。 本篇論文主要研究於二維光子晶體利用能帶分布圖檢測待測物的折射率。 在第一部分的研究中，我們在矽基板上製作二維光子晶體，以三種不同顏色的色光進行0.002到0.5莫耳濃度區間的葡萄糖水溶液折射率量測。我們將元件置於載台上並且將入射光以固定角度經由光纖照射於光子晶體生物感測器之區域。並以低成本光譜儀收集其反射訊號，以傳統方式量測其反射光譜之角度隨濃度變化、反射光譜之波長隨濃度變化之訊號。 其結果發現我們的二維光子晶體生物感測器以傳統方式之量測分析，在低解析度之光譜儀下其結果並無法反映待測物葡萄糖溶液之折射率。 在第二部分的研究中，我們一樣製做了二維光子晶體在矽基板上，由於二維光子晶體在橫截面上可視為多種不同周期之一維光子晶體，為此我們延續第一部分的實驗，將三種不同顏色的色光照射於裝載0.002到0.5莫耳濃度葡萄糖水溶液的光子晶體生物感測器上，並且將光子晶體生物感測器置於可旋轉之載台上調整其載台角度使入射光照射於不同的一維光子晶體周期上。並延續第一部分的實驗以傳統的角度變化、波長變化以及本篇的研究主題-能帶分布圖進行葡萄糖水溶液的折射率分析。結果發現在低解析度下的傳統方式量測分析，其結果受外在環境干擾嚴重。而光子晶體能帶分布圖則受惠於正規化的數據處理技巧，能不受外在環境影響並且以自校準的方式顯示出個別葡萄糖水溶液的折射率值，我們同時定義出感測器的敏感度和其量測極限，並且得到敏感度和量測之光子晶體周期成正比，量測極限會受到入射光波長影響及待測物本身光吸收率的影響。

Recent years, Iot (internet of things) has become a very popular topic in consumer electronics. Wearable device and various of sensors which construct the Iot makes the market have tremendous demand. Iot biosensing application such as food safety, medical and drug testing. It is attractive article of sensor product with cost-effective price. Biosensing technology such as 2 D PhC (photonic crystal) biosensor. The detection limit can reach to watery concentration. Although the high detection limit it reached, the measurement facility such as light source and monochromatic meter are still in high cost. Usage of low resolution detector and low cost light source but sill remain the sufficient precision is an important issue to promote the biosensor to consumer. In this thesis, the anatyle detection via 2 D PhC band diagram is studied. In the first part, we fabricated the 2 D PhC structure on silicon wafer. Three kinds of LED (light emitting diode) are used to measuring refractive index of glucose solution which the concentration range are 0.002 mole/L to 0.5 mole/L. The device is putting on the stage and fixing the angle of incident light. The LED illuminated the PhC biosensor sensing area via fiber. The reflect signal was collected by the cost-effective spectral meter. The traditional analysis method including angular spectra and spectral analysis was executed. The results found that our 2 D PhC biosensor cannot measure the glucose solution reflective index under the low resolution spectral meter with traditional analysis. In second part, the same 2 D PhC structure is fabricate on silicon wafer. Multi period grating can be measured by changing the incident direction on 2 D photonic crystal. Thus we extend the experiment in the first part. Measuring the 3 kinds LEDs and changing the glucose solution range from 0.002 mole/L to 0.5mole/L on the PhC biosensor. Changing the grating period by rotating the stage. Also, traditional measurement method employed and the main method in this thesis – band diagram analysis to analyze the reflective index of glucose concentration. Results shows that the traditional measurement method still interfered by noise. The PhC band diagram analysis benefits from the normalize process which can control the noise and presenting the refractive index with self-align rather than water reference. The sensor’s detection limit and sensitivity are also defined. The sensitivity is proportional to PhC period. The detection limit is effected by incident spectral and absorption of analyte.