Development of an evanescent-field fibre optic sensor for Escherichia coli O157:H7

An intensity-modulated fibre optic sensor was developed for Escherichia coli O157:H7. The interaction between the whole natural bacteria and the guided lightwave was carried out by means of evanescent-field coupling. A correlation between optical response and the current number of bacteria was achieved. The device sensitivity had been calibrated for initial number of bacteria (N(0)) from 10-800. The sensor sensitivity was 0.016 (+/-0.001) dB/h/N(0). The sensing mechanism starts together with the log phase leading the present sensor response to be five to ten times faster than conventional bacteriological techniques.