Biomolecule Detection Based On Giant Magnetoresistance (GMR) Biosensor

Giant Magnetoresistance (GMR) sensors used the superparamagneticmicrobeads as labels to detect biology signals which based on the theory thatthe resistance of GMR materials can reduce when it sensed the magnetic fieldof microbeads. Giant magnetoresistive (GMR) biochip using magnetic beadsas labels is a promising candidate for biosensing system, due to its highsignal-to-noise ratio, compatible with the established CMOS processing, highintegration, and multichannel detection. This dissertation aims to realize theapplication of GMR sensors for detection of protein and DNA.First we introduced the GMR sensor fabrication process, and the principleof works. A new structure of the GMR sensor was designed to improve thebehavior of detection for low concentration biomolecule. The characteristicsof GMR sensors were measured and analyzed by microbeads.AFP(alpha fetoprotein) test was considered as an important method forearly diagnosis of hepatitis B. We used GMR biosensor to make a qualitative detection for the target antigen-AFP which was marked withstreptavidin-coated magnetic microbeads. AFP samples of threeconcentrations gradient solution were detected. Then the test results wereanalyzed.Two genotypes of HBV viral DNA B-type and C-type were distinguishedby GMR biochips. First two genotypes labeled with magnetic beads wereamplified by polymerase chain reaction (PCR). Then different types of DNAprobes were fixed on the different areas of chips to detect DNA samples. Wecan distinguish the two different types of HBV viral DNA through thedifferent regions of the GMR sensor resistance change value comparisonsIn this paper we realize the application of GMR biosensor in diseasediagnosis.