Invasive infrared sensor for the determination of the cell number in a continuous fermentation of hybridomas

A new and simple device for the on-line determination of the total cell count in fermentation vessels is presented. It is based on fibre optic techniques, produces a constant infrared signal and determines the cell count via the scattered light. The linear range between the cell count and the infrared response lies between 1 X 10(5) and more than 2 X 10(6) cells per ml. This sensor shows good correlation between the cell count and the infrared response in fermentations with cell viability of more than 80%. The feeding pumps in these fermentations can be controlled via this sensor to get fermentation with stationary cell counts.