智慧電漿子實驗室晶片系統之核酸感測研發

Abstract

近年來，人口快速增長伴隨著社會老齡化，為醫療照護系統帶來日漸沉重之負擔。因應此社會現象，居家定點照護成為許多學術研究以及新創產業的熱門方向。透過適當的設計，結合消費性電子元件強大的軟硬體，以往僅能在實驗室運作的生物感測器將可以被引入居家生活中提供即時而精確的醫療診斷。 本論文旨在探索如何運用智慧型手機作為整合之核心平台，建構可攜式表面電漿共振生物感測器實驗室晶片系統。於論文第一部分，利用單股核糖核相對於雙股核糖核酸更能夠有效地避免鹽類誘發之金奈米粒子聚集特性，我們於智慧型手機上建構了一個核糖核酸檢測裝置。在此一平台，智慧型手機扮演了幾個重要的角色。首先，透過3.5釐米音訊孔與自製電路之整合，智慧型手機可以驅動650奈米之射源，並透過輸入電極接收雷射光訊號，來進行金奈米粒子吸收度量測。透過軟體鎖相放大器來解調射源之震盪訊號，百分之八十以上的環境雜訊可以被排除，使該平台成為一個具有-63 dB優良訊躁比的顯色儀。最後，所有資訊可以直接在自製之應用程式上被顯示、分析，不需要任何額外裝置。透過我們提出的平台，我們能夠在智慧型手機上，於十五分鐘內解析最低0.77 nM的核糖核酸樣品，甚至優於某些商用桌面型可見光－紫外光光譜儀在單一波長的解析極限。 接續第一部分的實驗，我們提出了一種全新的相位式表面電漿共振生物感測器。許多文獻指出，相位式表面電漿感測器比強度式更加的靈敏(約100倍)。然而，因為需要相位震盪器、易受到同徑雜訊影響以及需要過多光學組件等諸多議題的限制，相位式表面電漿感測器之商業化應用至今仍未成功，遑論手持式應用。然而，相位式表面電漿感測器的額外靈敏度，在定點照護中具有相當重要的價值。為此，本論文提出了剪干涉式表面電漿共振生物感測器。剪干涉式表面電漿共振生物感測器，具最小化同徑干擾效應、減少光學零組件需求、以及透過電流調變作為相位調等優點。為了處理強度與相位同頻率震盪的干涉訊號，本論文提出一種新的相位擷取方式。此方法，改良自泛用式鎖向放大器，可以在相位震盪深度(Δϕa)為3.83且已知雷射波長-電流調變係數(S)等特殊條件下，解調出相位資訊。在電漿層膜厚為47奈米的情況下，剪干涉式表面電漿共振生物感測器可以達到 1.26x10-6 RIU之最低解析度，約比強度式靈敏20倍。透過適體修飾以及心肌蛋白之檢測，本論文也初步展示剪干涉式表面電漿共振生物感測器之應用潛力，並提出一套結合嵌入式系統以及消費性電子元件之應用架構。

This thesis is dedicated to integrate consumer electronics devices (CED) with advanced plasmonic sensors into Lab-On-a-Chip system for point-of-care application, with a main focus on design of compact plasmonic sensor. In the first part of the thesis, a short strand DNA biosensor combining single-wavelength colorimetry and digital Lock-in Amplifier within a smartphone is proposed. The principle of the detection is that single strand DNA tends to protect gold nano-particle from salt induced aggregation, as compare to double strand DNA. The salt induced aggregation is then detected from absorbance at 650 nm wavelength. Using 3.5 mm audio channel to integrate laser driver and photo-detector, together with a tailor-made software lock-in amplifier (sLIA), we have achieved a 15 mer DNA detection down to 0.77 nM within 15 minutes on smartphone. Due to sLIA, the measurement noise-to-signal ratio is greatly reduce to -63 dB, which lead to four times smaller limit-of-detection as compared to a desktop UV-Vis spectrometer. Encouraged by the results of the first part, we proceed to explore the possibility of smartphone based interferometric plasmonic sensor. Conventionally, phase sensitive Surface Plasmon Resonance (SPR) biosensor is not viable outside laboratory setting due to cost and performance consideration. Therefore, to pursue portable SPR application with high sensitivity, in the second part of the thesis, a Shearing Interferometer based Surface Plasmon Resonance (SiSPR) biosensor, which has not been reported elsewhere, is proposed. The SiSPR chip uses shearing interferometer without the need of extra optical parts. This design together with differential interferometry greatly reduce noises. To avoid the use of costly phase modulator, a current induced sinusoidal wavelength modulation is applied with a novel phase extraction method. We demonstrate that the detection limit of the SiSPR, at 47 nm of plasmonic layer thickness is down to 1.26x10-6 RIU, about 20 times better than amplitude sensing. From our data, we estimate that SiSPR can be more sensitive if film thickness is near 49 nm. We have also demonstrated preliminary results on protein sensing using aptameric probe. The further integration of SiSPR with CED and future perspectives are incorporated in the end of the thesis.