| Since the fast development inthe researches of biomedical detection area in recent years, the biomedical sensors have been desired stronger capabilities as the tool of biosensing and chemical analysis. To obtain high quality information from biomedical tests, novel biomedical sensing techniques based on advanced sensing technology and new sensitive materials have attracted more and more investigation attentions. In recent years, there is a development trend that pursues automatic, integrate and continuous on-line sensing appearing in the biomedical sensor researches. In this circumstances, a kind of sized-miniarurized new biomedical sensors, the surface-affinity biosensor, which provide the label-free, specific and quantitative sensing capabilities in the concentration measurement of target biomolecules without requirements of enzyme and analyte labeling, has been widely investigated.In this thesis, we present two hot-spot works in the surface-affinity biomedical sensors. They are the surface plasmon resonance (SPR) biomedical sensor (Chapter2-4), and the graphene field-effect transistor (GFET) biomedical sensor (Chapter5-9), respectively. During the work of both SPR and GFET, a concept that integrates the sensing components as minimal as we can to realize the bio-information collection by using less instruments, smaller device, lower power consumption and saving samples.In detail, the work in this thesis that concerns SPR biomedical sensor investigation includes the contents as follow:1. By utilizing a portable spectrometer equipment, we design and fabricate a spectral (wavelength-interrogation) SPR sensor. The responses from the refractive index (RI) value changes on the SPR interface as well as the equivalent changes induced by surface-affinity of biomolecules can be detected by observing the attenuated total reflection (ATR) intensity of the polychromatic light beam on the wavelength band. 2. The biomedical sensing application is illustrated by functionalized the SPR sensitive film with Immunoglobulin G antibody. The experimental results demonstrated that our device processes a label-free and quantitative sensing potential of protein biomarkers.3. A noise-cancellation method is proposed by timely scanning the reference channel to provide a dynamically refreshed intensity baseline. In another section, the work on GFET biomedical sensor investigation basicallyincludes following contents:1. Graphene synthesis based on the chemical vapor deposition (CVD) method. By studying the CVD technology, a simplified and low-cost synthesis way is concluded to produce high-quality graphene material for GFET device fabrication.2. Device fabrication based on the Micro-Electro-Mechanical System(MEMS)techniques. The entire fabrication process of GFET sensor device is concluded in this work.3. The electrical characterization of graphene is investigated. Based on the experimental results of the transport characteristics of doping graphene, the application rule and optimization method of GFET sensor device is concluded.4. The biomedical sensor application potential is demonstrated by functionalize graphene with target analyte receptor. In this work, we conduct an aptamer-based sensing strategy to achieve a label-free, specific and quantitative sensing of a diagnostically important hormone biomarker Dehydroepiandrosterone (DHEA-S) bassed on a deeply investigation inthe biological mechanism of the interaction between biomolecules is investigated in this work. A new sensing strategy based on the competition between single strand DNA molecules hybridization and aptamer-analyte affinity is proposed. Meanwhile, we also find a new method to solve overcome the difficulty of former surface-affinity biosensor that small-molecule analytes are hardly to be detected in the diluted concentration. |
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