| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 93 === Owing to the tiny molecular weight and volume of biomolecules and very low physiologic concentration in biomolecular interaction analysis, it is important to improve the detection limit of biosensing. In this thesis, we integrate high sensitivity transducers (with or without fluorescence label) and developed electro-optical (E-O) signal processors to enhance the resolution of optical metrology system.
First, we develop an E-O detector in bio-medical detecting application. The E-O detector combines with a photomultiplier tube sensor and a developed circuit board including the analog current amplifier, analog to digital converter, and universal serial bus (USB) interface. The detector now can measure the light power down to 10-16W and has been used in the bio-luminescence system and biochip fluorescent scanning reader.
Moreover, a microfluid biochip is used to verify and the signal-to-noise ratio of the fluorescent signal is improved with the amplitude modulation lock-in amplifying technique with the help of dual-phase lock-in amplifier, and therefore the detection limit of the fluorescence measurement is improved with 20 times better then that of a conventional system. Lock-in amplifier is a key E-O device, so, we develop a home-made digital lock-in amplifier based on a home-made 32-bit digital signal processing board with USB 2.0 interface to realize the digital lock-in amplifier technique in real-time data transmission.
To develop label-free biosensing systems, we focus on high sensitivity surface plasmon resonance (SPR) biosensing to build a common-path SPR heterodyne interferometer with the above E-O devices. The SPR interferometer can detect the refractive index change of better than 10-6 by testing the nitrogen and argon gases. Besides, we compare the difference between the magneto-optical and E-O modulation light sources. Finally, a prototype of full-field heterodyne interferometer is developed.
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