The SFR vario offers online monitoring of oxygen, biomass and pH or CO2 - simultaneously. Online measured biomass data can be correlated with parameters like optical density, cell dry weight, or cell concentration. This way it is possible to get real-time information on e. g. OD600 development. The device optics can read out one oxygen and one pH or CO2 (CO2 Technical Data) sensor spots - integrated in the ready-to-use cultivation vessels - and also comprise a dedicated optical set-up for biomass monitoring. The oxygen uptake rate (OUR) can be calculated from the slope of the online oxygen measurements. The system has two long-lasting, rechargeable batteries, and is compatible with any standard shaking incubators. Up to 4 SFR vario can be controlled from the SFR vario software. Measurement data are transferred wirelessly via Bluetooth to a PC / notebook.