Measurement of the Viable Cell Density: Validation and Integration of On-Line and Off-Line Capacitance Biomass Monitors for Cell Culture Processes

Abstract

The quantity of biomass is commonly measured on-line and off-line in terms of cell numbers. To monitor cell growth on-line in a bioreactor, there are two main methods (Guan et al., 1998): (a) optical probes that do not discriminate between viable and dead cells; and (b) the radio-frequency impedance (RFI) method that counts living cells as capacitance. Off-line, cells are most frequently counted by haemocytometer. The RFI method, however, that could be quicker and more reproducible than the haemocytometer for estimating off-line cell numbers.