Impedance sensors embedded in culture media for early detection of bacteria growth

In this work, the ability of an impedance sensor to rapidly detect bacteria growth in a culture medium has been investigated. A test configuration with two electrodes embedded in a Petri dish has been proposed. Impedances corresponding to a sterile medium and one inoculated with bacteria have been measured and compared during the growth process. Remarkable differences have been observed in the time evolutions of the two behaviors. In particular, impedance behavior measured at 100 Hz allows such achievement after only 1 h. An equivalent circuit of the measured impedances have been proposed. Considerations regarding the effects of the bacteria growth on the components describing the electrode-medium interface have been reported. The variations of these elements have been identified as the more significant for the early detection. From these promising results, improved configurations consisting of a matrix of electrodes can be proposed for localized and rapid detection by means of automated analysis systems.