A high density microelectrode array biosensor for detection of E. coli O157:H7

A high density microelectrode array biosensor was developed for the detection of Escherichia coli O157:H7. The biosensor was fabricated from (1 0 0) silicon with a 2 μm layer of thermal oxide as an insulating layer, an active area of 9.6 mm2 and consists of an interdigitated gold electrode array. The sensor surface was functionalised for bacterial detection using heterobifunctional crosslinkers and immobilised polyclonal antibodies to create a biological sensing surface. Bacteria suspended in solution became attached to the immobilised antibodies when the biosensor was tested in liquid samples. The change in impedance caused by the bacteria was measured over a frequency range of 100 Hz-10 MHz. The biosensor was evaluated for E. coli O157:H7 detection in pure culture and inoculated food samples. The biosensor was able to discriminate between cellular concentrations of 104-107 CFU/mL and has applications in detecting pathogens in food samples.