This technology is based on measuring the change in impedance with interdigitated microelectrodes during the growth of target bacteria in a selective medium or measuring the change in cathodic peak current of oxygen during cell growth. The impedance method can detect viable Salmonella Typhimurium as low as 5 CFU/ml in less than 10 hours.

A group of impedance growth curves during the growth of Salmonella in SC/T/M broth. Initial cell number: (a) control, (b) 5, (c) 28, (d) 1.8×10², (e) 5.4×10³, (f) 5.3×10⁴, (g) 5.4×10⁵ CFU/ml.

The linear relationship between the logarithmic values of initial Salmonella cell numbers and the detection times obtained from the impedance growth curves in the tests with pure culture and milk samples.

C. Ruan, L. Yang, Y. Li. 2002. Rapid detection of viable Salmonella typhimurium in a selective medium by monitoring oxygen consumption with electrochemical cyclic voltammetry. J. Electroanal. Chem. 519, 33-38.

L. Yang, Y. Li, C. L. Griffis, M. G. Johnson. 2004. Interdigitated microelectrode (IME) impedance sensor for the detection of viable Salmonella typhimurium. Biosens. Bielectron. 19, 1139-1147.