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. while the cells are still attached to their microsupport, to monitor the changes 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 capacitance of the spent growth medium alone, still keeping the probe inserted in the bioreactor. This will make dielectric spectroscopy the first truly in situ, on-line, in real time, non-invasive measure of the biomass.