| Summary: | 碩士 === 國立臺北科技大學 === 有機高分子研究所 === 105 === Health care and preventive medicine that are all related to the sensor research have recently drawn much attention. Among various detection platforms, molecular sensors based on silicon field-effect-transistor(Si-FET)made by top-down device fabrication technology possess advantages such as high sensitivity, real-time detection and capacity for mass production. Furthermore, when modified with specific probe molecules, good sensing selectivity can be achieved. However, detection of trace amount of target molecules still presents a major challenge even with the present-day start-of-the-art sensing technology. A yet more difficult issue is that the target molecules commonly present in a large amount of analyte, e.g. Escherichia coli (E. coli) in bottled water, detection through microfluidic channels is impractical.
In this thesis work, E. coli was chosen as the target antigen. The interaction between antigen and antibody interaction was detected using Si-FETs with the channel surface being modified with E. coli antibody. The E. coli in the analyte was attracted to the channel surface by using hydrodynamics induced by electrothermal flow and dielectrophoresis. An AC electric field was applied on a pair of electrodes to produce a field gradient, causing the dielectrophoresis flow. On the other hand, the current induced Joule heat created a temperature gradient that caused electrothermal flow. A combined effect is a wide range of circulating flow.
Electric field and temperature field distribution in the analyte was calculated for various shapes of metal electrode structures such as veins and tip, and the results served as a guide for the electrode design in the experiments. It was found that when a 10 MHz, 10 V voltage was applied on the electrodes of veins and tip structures, E.coli was formed a stable and rapid circulation convection flow. Finally, this molecule-manipulation mechanism was applied to Si-FET sensor with a pair of electrokinetic electrodes. By optical microscope observation, it is found that, with electrokinetic manipulation, the density of E. coli bound to the antibody-modified channel surface increased by approximately 10 times.
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