An Affinity Sensor Improved by EWOD Actuator-based Microfluidic Chip

• Main Authors: Chin-Wei Liu, 劉晉維
• Other Authors: Hsien-Chang Chang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/34391013105185284527

碩士 === 國立成功大學 === 奈米科技暨微系統工程研究所 === 97 === Some specific proteins existing and correlating with disease in the blood or the food, its concentration changes or structural change, is considered as the symbol of disease development. On clinic, immunoassay is applied to detect these substances and measure the antibody or antigen concentrations owing to their high bio-specific recognition interaction with their complementary target. In fact, the drawback of immune analytical instrument which based on optical method not only is high price and complicated operation, but false negative detection is often occurred. Among this, the fail in eluting processes for cleaning away the unbonding substances to be the main reason can be considered. To promote this, a microfluidic immuno-chip which is made by micro electro-mechanical technology and combining two zones that are modified (1) a series of insulator-coated electrodes as electro-wetting on dielectric (EWOD) construction and (2) a antibody (IgG) - modified gold electrode. The former is designed for creating a droplet containing target sample and transporting it in chip by EWOD. By stepwise operating the electrodes rapidly to be hydrophilic and hydrophobic, the sample was moved to the sensing zone. The later is for detecting the concentration of target sample based on measuring the extent of impedance change. The self-assembly monolayer, 11-MUA, possessing a thiol group in one side will spontaneously bind onto gold electrode and a carboxylic group in the other side was activated by the agents of EDC/NHS that may promote the bind with antibody through its amino group. After the blocking treatment with bovine albumin serum, this zone will be used as for detecting Protein A. we also treated the intersection of zone 1 and 2 by oxygen plasma to allow the sensing zone to be more hydrophilic that will spontaneously achieve movement and promote the feasibility in sample transportation and electrode elution. Moreover, AC eletroosmosis flow (ACEOF) was introduced by setting the sensing electrode at 8 Vpp with 500 Hz before detection that will reduce the time for affinity reaction dawn to be 50 sec from 1 hr. As a result, the resistance change (ΔRet) by electro-chemical impedance spectroscopy for detecting protein A showed a linear correlation in the range of 1-50 ng/ml. The microfluidic system can be systemized for multiplex immuno-detection chip in the future.