Oxygen is the essential element of life and its measurement plays a central role in the control of biological processes such as fermentations. In combination with bioprocess software (e.g. BlueVIS), essential respiratory parameters such as the oxygen uptake rate (OUR) or the RQ (respiratory quotient) can not only be determined directly, but also calculated automatically. This data can also be used for process optimization. BlueSens analyzers are suitable for bioreactors of any size, from laboratory to industrial scale. Conversion and transmission errors can be avoided, as the same measurement technology is used in the scale-up process.