DIELECTRIC-SPECTROSCOPY OF MAMMALIAN-CELLS .2. SIMULTANEOUS IN-SITU EVALUATION BY APERTURE IMPEDANCE PULSE SPECTROSCOPY AND LOW-FREQUENCY DIELECTRIC-SPECTROSCOPY OF THE BIOMASS OF HTC CELLS ON CYTODEX-3

Low-frequency dielectric spectroscopy has been used in situ, i.e. whil e the cells are still attached to their microsupport, to monitor the c hanges of biomass accompanying the growth of anchorage-dependent cells . This method, when compared to Aperture Impedance Pulse Spectroscopy (also called electronic sizing), is characterized by a somewhat lower degree of resolution. Suggestions are made on how to determine the cap acitance of the spent growth medium alone, still keeping the probe ins erted in the bioreactor. This will make dielectric spectroscopy the fi rst truly in situ, on-line, in real time, non-invasive measure of the biomass.