Other Publications (1)
Articles by Valentin Jossen in JoVE
Power Input Measurements in Stirred Bioreactors at Laboratory Scale Stephan C. Kaiser1, Sören Werner2, Valentin Jossen2, Katharina Blaschczok2, Dieter Eibl2 1Finesse, Thermo Fisher Scientific, 2Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences, School of Life Sciences and Facility Management The power input in stirred bioreactors can be measured through the torque that acts on the impeller shaft during rotation. This manuscript describes how an air bearing can be used to effectively reduce friction losses observed in mechanical seals and improve the accuracy of power input measurements in small-scale vessels.
Other articles by Valentin Jossen on PubMed
Novel Probes for PH and Dissolved Oxygen Measurements in Cultivations from Millilitre to Benchtop Scale Applied Microbiology and Biotechnology. | Pubmed ID: 26995606 pH value and the concentration of dissolved oxygen (DO) are key parameters to monitor and control cell growth in cultivation studies. Reliable, robust and accurate methods to measure these parameters in cultivation systems in real time guarantee high product yield and quality. This mini-review summarises the current state of the art of pH and DO sensors that are applied to bioprocesses from millilitre to benchtop scale by means of a short introduction on measuring principles and selected applications. Special emphasis is placed on single-use bioreactors, which have been increasingly employed in bioprocess development and production in recent years. Working principles, applications and the particular requirements of sensors in these cultivation systems are given. In such processes, optical sensors for pH and DO are often preferred to electrochemical probes, as they allow semi-invasive measurements and can be miniaturised to micrometre scale or lower. In addition, selected measuring principles of novel sensing technologies for pH and DO are discussed. These include solid-state sensors and miniaturised devices that are not yet commercially available, but show promising characteristics for possible use in bioprocesses in the near future.