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Impedimetric Biosensor for the Rapid Detection of Escherichia coli O157:H7

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  037060,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14181) @2003
Authors:   Stephen Radke, Evangelyn Alocilja
Keywords:   Biosensor, Pathogen, Impedance Spectroscopy, Microfabrication

A biosensor for E. coli O157:H7 detection was developed which detected the change in impedance caused by the presence of cells immobilized on interdigitated gold electrodes. The sensor was fabricated from a 100 Silicon wafer with a 2m layer of SiO2 as an insulating layer. The sensor active area contained interdigital gold electrodes deposited over the SiO2 using photolithographic processing methods. Analyte specific antibodies were immobilized to the SiO2 in between the electrodes creating a biological sensing surface. Using impedance spectroscopy, the impedance across the interdigital electrodes was measured after immersing the biosensor in solution. Bacteria cells present in solution attached to antibodies and became tethered to the sensor surface. Immobilized bacteria cells changed the dielectric constant of the media between the electrodes thereby causing a change in measured impedance. The biosensor was able to discriminate between different cellular concentrations from 102 - 107 CFU/mL in pure culture with a detection time of 5 minutes. The design, modeling, fabrication and testing of the biosensor is discussed along with the implications of these findings towards further biosensor development.

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