多通道表面電漿共振矽波導感測晶片系統

Abstract

在近年來、許多生物與化學感測器的研究上使用了表面電漿子的概念。 其原因於這種感測器有高的靈敏度、無須螢光標。表面電漿共振感測器 ( Surface Plasmon Resonance Sensor) 是一種光學式的生物/化學感測器。光波導元件讓此表面電將共振感測器微小化、不再侷限在實驗室。 在本論文研究中, 我們架設了一套表面電漿共振矩形光波導式的生物感測系統。多通道的設計與特殊的光學平台讓感測器可以在一次取多種感測樣本。光波導感測器採用微機電製程、主要結構為利用半導體製程中的電漿輔助氣相沈積法(PECVD)製造摻鍺二氧化矽材料，做為光波導材料，研製SPR生物感測晶片。我們取先前的研究所得到的最佳摻雜濃度與金模尺寸來製造晶片。在表面電漿共振感測器，我們採用厚度為五十奈米長度為兩百微米的金膜用電子束鍍膜在矩形的光波道上。感測晶片的大小為一公分乘一公分。波導導光處需要表面需要拋光才能達到均勻的光場強度。一個晶片上有多個金膜可以同時間做多種不同感測。 此研究中我們為量測波導式的表面電漿共振感測器建立了精密的六軸光學量測平台系統。此平台系統有多種的功能。Single detection波導的感測使用物鏡直接打光進入波導然後用另一個物鏡放大輸出的光線。此方法使用了全波段的白光與光譜儀感測表面電漿之共振頻率的偏移。多通道的光波導量測採用了兩種方法。一種方法是採用圓柱透鏡把雷射的光聚焦在光波導裡。另一種是用光纖把全波段的白光(鎢絲燈 或是微小化的發光二極體)導到波導裡。收光的部分採用光纖偶合到光譜儀或是電荷耦合元件。收光前需要有偏極片濾掉TE成分的光線。

Biosensors using guided wave have been very popular in the past few years due to its high sensitivity and possible commercial opportunity. Surface plasmon resonance (SPR) as basic transduction method for chemical sensing is quite well-known. SPR sensors have the advantages of label-free and real-time detection. The waveguide configuration allowed SPR detection miniaturized, unlike traditional angle-modulated SPR detection which is limited in a standard lab-size room. The waveguide was manufactured by semiconductor technique which can be used for mass production. An SPR optical sensor system based on ridged-waveguides on a precise optical bench was designed and built in this thesis. Multi-channel design and specialized optical bench allowed the sensor to perform multiple sensing. The waveguide sensors fabricated by MEMS technology consisted of a 10μm SiO2 substrate layer (n= 1.469), 10μm Ge doped SiO2 channel guide (n= 1.492), both are produced by plasmon enhanced chemical vapor deposition (PECVD) and wet etching standard semiconductor manufacturing procedure. Optimal process parameters had been acquired during previous studies to understand the resultant refractive index and doping concentration and dimensional specifications . A 50 nm gold thin film, 500μm in length was placed on top of ridge waveguide and SPR signal detections using E-beam lithography process. The waveguide chip was 1cm x 1cm in dimension. A surface polishing was needed for an even distribution of light focusing into the waveguide. Obtaining data from SPR waveguide sensor required a precise measuring platform with various degrees of freedom. In this thesis, different platforms were built for different applications. End-firing method was built with two V objective lenses on precise six-degree moving stage to obtain single channel detection. Broadband light and spectrometer were used in this kind of detection for observing the change of surface plasmon wavelength peak. For multiple detection, two methods were been used. For focusing light source (633nm laser) into the waveguide, in this method, a cylindrical lens for focusing. Broadband light source (Tungsten light or miniaturized LED), a parallel bundle of fiber were used, again those fiber bundles were mounted onto precise six-degree moving stage. The light from SPR waveguide was collected by spectrometer. A polarizer was put in between the waveguide and light detector to ensure the TM polarized direction. Various concentrations of glycerol and glucose were tested on two different configurations: single channel configuration and multi-channel configuration. Transmission loss due to SPR spectrum in comparison to the aero environment is calculated from transmission spectrum obtained from spectrometer. A transmission loss spectrum of nano particles deposited on gold sensing layer was demonstrated using the multi-channel configuration.