SPR光學感測技術之橫向傳播理論於生醫晶片之研究

The Lateral Propagation Theory of Surface Plasmon Resonance for Novel Biochip Detection System

宋致祥(Zhi-Hsiang Song)

指導教授 ： 林啟萬

國立臺灣大學/工學院/醫學工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00135

摘要

表面電漿共振（surface plasmon resonance，SPR）現象應用於氣體、化學、生物分子感測技術的研究已經有數十年歷史。以往SPR光學檢測的主要範圍在垂直介面200nm內之深度分析，偵測結果也屬於光點區域的平均現象。又針對生物晶片之低濃度樣本檢測，大多限於改善光學系統的設計方式，在感測原理上未見有創新發展。事實上，SPR的能量分布在垂直介面及平行介面方向皆呈指數衰減，當入射光波長介於可見光至近紅外光範圍且達到SPR共振態時，垂直穿透深度變動不大，只有約100~200nm區域，而沿著介面的橫向傳播長度可達數十至數百µm，幾乎高了三個數量級，這個特性延伸出以SPR之橫向傳播特性作為表面探測器的構想。

本論文為探究SPR的橫向傳播（SEW）現象，由理論模擬開始，目的在設計適當的感測晶片、激發及偵測光路，使用雙稜鏡耦合法結合衰減強度偵測光路，藉由增加實際感測面積之方式，在沿金屬或表面鍍膜的傳播距離內，觀察生醫晶片表面因生物分子反應結合引起的訊號變動。另外還有共振波長偵測架構，在固定之稜鏡間距內，觀察SPR共振波長之變化情形來推得表面物質反應狀況。

根據評估，衰減強度偵測光路初步可達到的靈敏度約1.05*10^-5 RIU（波長790nm時），共振波長偵測架構可達到的靈敏度約2.2*10^-5 RIU（稜鏡間距＝40µm時、金膜感測面）。若波長繼續拉長至紅外光波段，則藉由增加實際感測面積提高解析度之效果會更顯著。目前已成永狻

關鍵字

生醫感測器 ； 表面電漿共振 ； 傳播長度 ； 橫向傳播

並列摘要

The surface plasmon resonance (SPR) phenomenon was described in 1959 and has been used for decades. SPR biosensors are optical sensors using polarized surface electromagnetic waves (SEW) to probe molecular interactions between metal film surface and dielectric medium. Generally, the sensing area of SPR is limited in vertical penetration depth. Actually, there still exists laterally propagating SEW which can enlarge (depending on the wavelength and the refractive index of the interface type) the sensing area of SPR for almost 103 times! Yet the idea of using SEW as a sensitive probe has never been applied to bio-sensing.

In this thesis, we investigated the lateral SPR propagation theory and implemented a novel optical SPR detection system, including biochip fabrication. Using two-prism coupling method to excite SPR, we also design two kinds of optical system: intensity detection system (at fixed wavelength, measuring the propagation length variation) and resonant wavelength detection system (at fixed propagation length, measuring the resonant wavelength variation). We can find lateral SPR phenomenon then track binding conditions on the surface.

Propagation length is increasing with excitation wavelength. The ability to sample a surface for much longer distance than penetration depth can enhance the detection sensitivity for ~1.05*10^-5 RIU at λ=790nm and for ~2.2*10^-5 RIU at gold film with propagation length=40µm.

In the future, this novel system can apply for the high throughput, high sensitivity applications of multi-channel SPR sensing devices.

並列關鍵字

biosensor ； biochip ； surface plasmon resonance ； propagation length ； lateral propagation

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