Impedance measurement
Impedance measurement, which can be used to detect small electrical variations and detect the presence of microorganisms long before a colony is visible in the culture, is the principle of the Bactometer test. The molecules of the culture medium (proteins, carbohydrates, etc.), which are electrically neutral or slightly ionized, are transformed by the action of the microorganisms into several molecules with higher mobility and electrical charge (amino acids, lactate, etc.). These modifications can be measured between two electrodes in the culture medium.