Cell Density monitoring comprised two technologies: viable cell density and total cell density. The viable cell density measurement is based on permittivity and gives the user a deep insight on their cell culture or fermentation. It’s insensitive to microcarriers and cell debris. The total cell density measurement is based on turbidity, resp. on optical density measurement at NIR (Near Infra-Red) wavelengths. The measuring loops for viable and total cell density monitoring consist of an Incyte resp. Dencytee sensor, an individual pre-amplifier and a Control Unit. The controller can display both parameters at once using the 2 (Arc View 265) or 4 (Arc View 465, 465 XL) channel inputs. The Cell Density ComBox is designed for small space requirements or a bench and Arc pH and DO sensors with a wireless module can be displayed on the controller giving the user the ability to regard all relevant parameters of a cell culture or fermentation on one screen.