Bioreactors are nowadays used to produce a variety of pharmaceuticals, food supplements and other chemical substances. Monitoring of the process conditions is necessary to keep the processes running stable and effective. For this purpose, physical parameters such as pH and temperature, but also the concentration of certain substances must be continuously monitored.

The most commonly used carbon source in bioprocesses is glucose and a study was conducted to determine the suitability of an affinity viscometric glucose sensor developed at IHP for monitoring glucose in diabetic patients [Theuer et al. 2017]. It was found that the fluctuating electrolyte concentrations can cause a strong drift of the sensor signal. Based on this experience, optical biosensors such as those based on the Raman principle currently seem to be the most suitable for bioprocess monitoring [Kögler et al. 2018].