CMOS-BioMEMS製程之壓阻式懸臂樑蘭花病毒感測器

Abstract

蘭花為台灣非常具有代表性的經濟作物。據統計，2012年蘭花出口總值為一億六千萬美金。故關於蘭花培養照護和出口前的品質把關相當地重要，因此如果能快速而準確的檢測出蘭花病毒，對台灣蘭花產業會有相當的助益。本論文致力於利用壓阻機制之微懸臂樑開發出一具有快速、低成本及可攜式的蘭花病毒感測器。本研究選擇齒舌蘭輪斑病毒(Odontoglossum ringspot tobamovirus,ORSV)做為檢測目標，因其為感染蘭花最為嚴重的病毒之一，造成蘭花出口產業重大經濟損失。 本研究使用惠斯通電橋電路設計(Wheatstone bridge)，將懸臂樑上因生物鍵結導致的阻值變化轉變為電壓訊號變化，再利用後端濾波放大電路將訊號濾波放大以利判讀檢測結果。利用整合於電橋中的參考懸臂樑，所測得的訊號得以更真實反應生物分子間在懸臂樑表面的專一性辨識所導致懸臂樑造成的形變 (Deflection)。本研究中使用ORSV-IgG為生物標定物 (Bio-marker)，利用自組裝分子技術 (Self-assembly monolayer, SAM)將其固定在微懸臂樑表面，隨後將ORSV 病毒注入使其產生生物專一性結合。本感測器檢測極限經實驗量測為50 ng/μl且擁有良好的專一性 (Specificity)。 由於壓阻式懸臂樑感測器會有電流持續通過懸臂樑導致熱雜訊相對嚴重，針對此問題本研究使用間隔量測(discrete measurement)來做改善。而對於複合材料懸臂樑機械性質的量測(彈性係數)，本論文亦測試及比較不同的量測方法包括靜態及動態量測方式。 此懸臂樑式生物感測器是基於台積電CMOS-MEMS 2P4M製程加上BioMEMS後製程所製成，配合簡單的電路設計可擁有不需額外標記、快速、和可攜式等優點，並具備成為即時現場照護(point-of-care)檢測平台之潛力。

This thesis is devoted to develop a rapid, low-cost, portable device for on-site diagnosis of Odontoglossum ringspot tobamovirus (ORSV), one of the most prevalent viruses in Orchids. Orchids are the most important economic crops in Taiwan; it has more than 164 million of US dollars in export value in 2012. The cantilever sensor with piezoresistive mechanism possesses the advantage of portable, rapid and accuracy that can be utilized in on-site virus detection. Wheatstone bridge with signal readout system is used to detect the small bio-signal. By integrating reference cantilevers as mechanical filter in the sensor, the detection result is more reliable since the signal change is mostly contributed from biomolecule-recognition between ORSV antibody and antigen. The ORSV detection limit of the cantilever sensor was measured at 50 ng/μl and showed great specificity. One of the problems in piezoresistive cantilever biosensor is thermal drift problem since the electric currents flowing through the piezoresistors, caused additional heat dissipation. The discrete measurement was designed to solve the problem. Different methods of characterize the stiffness of composite cantilever were also conducted and compare in the thesis. The device further adapts commercially-available TSMC 0.35 2P4M CMOS technology with BioMEMS post-processes, showing its potential as a low-cost, rapid, label-free and point-of-care (POC) device for orchid virus (ORSV) detection.