Theory
The technique is based on the findings of pioneer researchers such as Fricke (1936), Schwan (1950) and Hanai (1960), who demonstrated the relationship between the biomass volume fraction and the variation of the medium dielectric permittivity, in the beta dispertion frequency rage
Under the influence of an electric field between two electrodes, cells with intact plasma membranes are polarized and behave as tiny capacitors. The resulting capacitance is measured between a second pair of electrode pair and can be accurately correlated to the biomass concentration. Unlike conventional optical instruments, the system only responds to living cells and is not sensitive to gas bubbles, microcarriers, cell debris and other particles in suspension.