Impedance Measurement in the Culture Solution of Growing Bacteria

Characteristics of impedance changes measured by four- and two-electrode methods

Abstract

The four-electrode method has many advantages in monitoring the impedance change in the solution of growing bacteria. To examine the reason for good reproducibility, the characteristics of impedance change are measured by changing the material of metal electrodes, the length between electrodes, source frequency and amplitude of applied constant current, as well as the magnitude of the series resistance R₀. The R₀ is inserted to obtain constant amplitude of current. The results are summarized as follows :
(1) To monitor the rate of impedance change in the solution, the constant current method is convenient.
(2) The four-electrode method used together with constant current can give stable impedance change for any metal wire electrodes with 0.7 mmφ.
(3) Cheap stainless steel wire is favorable for metal electrodes.