MEMS biosensor for detection of Escherichia coli O157:H7 in food products
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Escherichia coli O157:H7, is one of the most common pathogens that has caused several outbreaks in recent years. In 2010-11 there were 5 outbreaks of E.coli and thousands were victim of it. Thus there is an immediate need for sensors capable of rapid detection of this pathogenic strains of E.coli. To detect the presence of E.coli O157:H7 a MEMS based biosensor has been designed and fabricated. It consists of planar interdigitated array of microelectrodes (IDAM) and a microchannel. The surface of the microelectrodes is modified using goat anti-E.coli polyclonal IgG antibody. As the bacterium cells come in contact it binds to the antibody. This binding changes the dielectric property of the electrodes, resulting in an impedance change. This change is measured using an impedance analyzer. Another variation of this biosensor has been proposed in this thesis. This design consists of two arrays of 3-dimensional electrodes and a microchannel with multiple inlets and outlets. In this design dielectrophoresis is utilized to separate unwanted materials from the cells to increase the sensitivity of the biosensor. From the analysis it was found that the biosensor is sensitive to varying concentration of E.coli samples and the lowest detection limit of the biosensor is 3x103CFU/ml. Also it was established that the total detection time for this biosensor is less than 30 minutes which is rapid compared to the conventional ways of detection.