Investigation of targeted biomolecules in a micro-fluxgate-based bio-sensing system.

An investigation of targeted biomolecules was accomplished by combining a micro-fluxgate-based bio-sensing system and Dynabeads. The fluxgate sensor for biomolecule detection was fabricated by Micro Electro-Mechanical system technology, including thick photoresist lithography, electroplating and chemical wet etching. The magnetic core of the sensor was made of Fe-based amorphous ribbon core and three dimension solenoid coils were used as magnetic sensitive elements. The micro-fluxgate-based bio-sensing system was characterized firstly in different concentrations of Dynabeads, and a concentration as low as 100 ng/ml was detected with an external dc magnetic field in the range of 525 μT to 875 μT. Sandwich assays are performed using antibody-antigen pair combination of biotin-streptavidin on a separated Au film substrate surface with a self-assembled layer. Detection of Alpha Fetoprotein antigens with different concentrations was performed and a minimum detectable concentration of 1 pg/ml was achieved by the bio-sensing system. It is of considerable interest due to its potential application in the biomedical field based on known specific binding of target and labels.