An innovative detecting way of Escherichia coli O157H:H7 by a micro-fluxgate-based bio-sensing system

A novel bio-sensing system based on a micro-fluxgate and use of magnetic beads labels was developed for detection of Escherichia coli O157H:H7. The micro fluxgate sensor was fabricated using standard microfabrication processes. Magnetic core of the sensor was made using Fe-based amorphous ribbon core and a 3-D magnetic sensitive element was made of Cu solenoid coils. Response of the micro-fluxgate-based bio-sensing system to superparamagnetic Dynabead was first evaluated with different concentrations of Dynabeads. It was found that a concentration as low as 10   ng/ml could be detected with an external dc magnetic field ranging from 450   μT to 700   μT. Double antibody sandwich assay was employed in preparation of E. coli O157H:H7 samples. Detection of E. coli O157H:H7 antigens at different concentrations were demonstrated. A minimum detectable concentration of 100   CFU/ml was observed for this bio-sensing system. On account of the detection performance and other advantages such as miniaturization, portability and stability, this bio-sensing system is a potential candidate for rapid analysis E. coli O157:H7 and other pathogenic bacteria . It is also of considerable interest for biomedical applications employing known specific binding of target and labels.