The Detection of E. coli and S. aureus on Sensors without Immobilization by Using Impedance Spectroscopy

Abstract

The impedance spectroscopy method (AC f = 4–8 MHz at a constant amplitude of 1 V) and Pt-IDE sensors were used to detect and monitor different concentrations (103, 106, and 109 CFU/mL) of both live and dead bacteria cells (Escherichia coli and Staphylococcus aureus). The analysis of the impedance spectra shows the differences in resistance with increasing concentrations for both types of bacteria and the presence of characteristic changes in the frequency range 10–100 kHz. The presence of live bacteria led to a decrease in the impedance value compared to dead cells, and the value of Rs + Rct decreased about two times.